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								    <h1 id="mainTitle">OWL Web Ontology Language<br />

								        Guide</h1>

								    <h2><a id="w3c-doctype" name="w3c-doctype"></a>

								        W3C Candidate Recommendation 18 August 2003</h2>

								    <dl>

								      <dt>This version: </dt>

								      	<dd><a href="http://www.w3.org/TR/2003/CR-owl-guide-20030818/">

								            http://www.w3.org/TR/2003/CR-owl-guide-20030818/

									    </a>

									</dd>

								      <dt>Latest version: </dt>

								      	<dd><a href="http://www.w3.org/TR/owl-guide/">

								            http://www.w3.org/TR/owl-guide/

									    </a>

								        </dd>

								      <dt>Previous version:</dt>

								      	<dd><a href="http://www.w3.org/TR/2003/WD-owl-guide-20030331/">

								            http://www.w3.org/TR/2003/WD-owl-guide-20030331/

									    </a>

								        </dd>

								      <dt>Editors:</dt>

								      	<dd>

								      	  Michael K. Smith, Electronic Data Systems,

								          <img align="middle" src="Email.Michael.K.Smith.gif"

									       alt="Michael dot Smith at e d s dot com"/> <br />

								      	  Chris Welty, IBM Research,

									  <img align="middle" src="Email.Chris.Welty.gif"

									       alt="Chris dot Welty at u s dot ibm dot com"/> <br />

								      	  Deborah L. McGuinness, Stanford University,

								          <img align="middle" src="Email.Deborah.McGuinness.gif"

									       alt="d l m at k s l dot stanford dot edu"/> <br />

								      	</dd>

								   </dl>

								   <p class="copyright"><a

								      href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">

								      Copyright</a> &#xa9;2003 <a

								      href="http://www.w3.org/"><acronym

								      title="World Wide Web Consortium">W3C</acronym></a><sup>&#xae;</sup>

								      (<a href="http://www.lcs.mit.edu/"><acronym

								      title="Massachusetts Institute of Technology">MIT</acronym></a>,

								      <a href="http://www.ercim.org/">

								      <acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym>

								      </a>, <a href="http://www.keio.ac.jp/">Keio</a>),

								      All Rights Reserved. W3C

								      <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">

								      liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">

								      trademark</a>, <a href="http://www.w3.org/Consortium/Legal/copyright-documents">

								      document use</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-software">

								      software licensing</a> rules apply.</p>


								    <hr title="Separator for header" />

								  </div>


								<h2><a name="Abstract" id="Abstract">Abstract</a></h2>


								<p>

								The World Wide Web as it is currently constituted resembles a poorly

								mapped geography.  Our insight into the documents and capabilities

								available are based on keyword searches, abetted by clever use of

								document connectivity and usage patterns.  The sheer mass of this data

								is unmanageable without powerful tool support.  In order to map this

								terrain more precisely, computational agents require machine-readable

								descriptions of the content and capabilities of Web accessible

								resources.  These descriptions must be in addition to the

								human-readable versions of that information.

								</p>


								<p>

								The OWL Web Ontology Language is intended to provide a language that

								can be used to describe the classes and relations between them that

								are inherent in Web documents and applications.

								</p>


								<p>

								This document demonstrates the use of the OWL language to

								</p>


								<ol>

								<li>formalize a domain by defining classes and properties of those classes,</li>

								<li>define individuals and assert properties about them, and</li>

								<li>reason about these classes and individuals to the degree permitted

								by the formal semantics of the OWL language.</li>

								</ol>


								<p>

								The sections are organized to present an incremental definition of a

								set of classes, properties and individuals, beginning with the

								fundamentals and proceeding to more complex language components.

								</p>


								<h2><a id="status" name="status"></a>Status of this document</h2>

								<div class="status">


								<p><em>This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at http://www.w3.org/TR/.</em></p>


								<p><em>Publication as a Candidate Recommendation does not imply

								endorsement by the W3C Membership. This is a draft document and may be

								updated, replaced or obsoleted by other documents at any time. It is

								inappropriate to cite this document as other than "work in

								progress".</em></p>


								<p>This draft is one of <a href=

								"http://www.w3.org/TR/2003/CR-owl-features-20030818/#s1.1">six

								parts</a> of the <a

								href="http://www.w3.org/2003/06/Process-20030618/tr.html#cfi">Candidate

								Recommendation</a> (CR) for OWL, the Web Ontology Language.  It has

								been developed by the <a href="http://www.w3.org/2001/sw/WebOnt/">Web

								Ontology Working Group</a> as part of the <a

								href="http://www.w3.org/2001/sw/">W3C Semantic Web Activity</a> (<a

								href="http://www.w3.org/2001/sw/Activity">Activity Statement</a>, <a

								href="http://www.w3.org/2001/sw/WebOnt/charter">Group Charter</a>) for

								publication on 18 August 2003.  </p>


								<p>The design of OWL expressed in earlier versions of these documents

								has been widely reviewed and satisfies the Working Group's technical

								requirements.  The Working Group has addressed <a

								href="http://lists.w3.org/Archives/Public/public-webont-comments/">

								all comments received</a>, making changes as necessary.  Changes to

								this document since the <a

								href="http://www.w3.org/TR/2003/WD-owl-guide-20030331/">Last Call

								Working Draft</a> are detailed in the <a href="#AppendixD">change log</a>.

								</p>


								<p>The Working Group now hopes to gather experience from the growing

								number of <a href="http://www.w3.org/2001/sw/WebOnt/impls">OWL

								implementations</a> in order to increase confidence in the language

								and meet specific <a

								href="http://www.w3.org/2001/sw/WebOnt/impls#exit">exit criteria</a>.

								This CR period will extend until at least <strong><span

								class="commentsDue date">20 September 2003</span></strong>.  After

								that date, when and if the exit criteria are met, the group intends to

								request <a

								href="http://www.w3.org/2003/06/Process-20030618/tr.html#RecsPR">

								Proposed Recommendation</a> status.</p>


								<p>Please send reports of implementation experience to <a

								href="mailto:public-webont-comments@w3.org">public-webont-comments@w3.org</a>

								(<a

								href="http://lists.w3.org/Archives/Public/public-webont-comments/">archive</a>).

								Reports of any success or difficulty with the <a

								href="http://www.w3.org/TR/2003/CR-owl-test-20030818/">Test Cases</a>

								are encouraged, and reports received by 20 September 2003 will be

								particularly helpful.  General discussion of related technology is

								welcome at <a href="mailto:www-rdf-logic@w3.org"

								shape="rect">www-rdf-logic@w3.org</a> (<a

								href="http://lists.w3.org/Archives/Public/www-rdf-logic/"

								shape="rect">archive</a>).  </p>


								<p>Although OWL is essentially stable, later versions of these

								documents are expected to contain minor improvements.  The <a

								href="http://www.w3.org/2002/03owlt/">test site</a> is likely to

								include new, clarifying tests, even during this CR period.

								Additionally, the design of OWL depends in part on the design of RDF,

								and at this time the relevant RDF specifications are only Working

								Drafts.  It is therefore possible that unanticipated changes in RDF

								may require changes to OWL.</p>


								<p>The W3C maintains a list of <a

								href="http://www.w3.org/2001/sw/WebOnt/discl" rel="disclosure">any

								patent disclosures related to this work</a>.</p>


								</div>


								<hr />


								<!-- tag syntax.  Drop initial 'the', delete all spaces.

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								<h1><a name="Contents" id="Contents">Contents</a></h1>


								<ul>

								  <li><a href="#Abstract">Abstract</a></li>

								  <li><a href="#status">Status of This Document</a></li>

								  <li><a href="#Contents">Contents</a></li>

								  <li><a href="#Introduction">1. Introduction</a>

								    <ul>

								      <li><a href="#OwlVarieties">1.1. The Species of OWL</a></li>

								      <li><a href="#StructureOfDoc">1.2. Structure of the Document</a></li>

								    </ul></li>

								  <li><a href="#StructureOfOntologies">2. The Structure of Ontologies</a>

								    <ul>

								      <li><a href="#Namespaces">2.1. Namespaces </a></li>

								      <li><a href="#OntologyHeaders">2.2. Ontology Headers</a></li>

								      <li><a href="#Privacy">2.3. Data Aggregation and Privacy</a></li>

								    </ul></li>

								  <li><a href="#BasicDefinitions">3. Basic Elements</a>

								    <ul>

								      <li><a href="#SimpleClasses">3.1. Simple Classes and Individuals</a>

								      	<ul>

								      	  <li><a href="#DefiningSimpleClasses">3.1.1. Simple Named Classes </a></li>

								      	  <li><a href="#DefiningIndividuals">3.1.2. Individuals </a></li>

								      	  <li><a href="#DesignForUse">3.1.3. Design for Use</a></li>

								      	</ul></li>

								      <li><a href="#SimpleProperties">3.2. Simple Properties </a>

								      	<ul>

								      	  <li><a href="#DefiningProperties">3.2.1. Defining Properties </a> </li>

								      	  <li><a href="#Datatypes1">3.2.2. Properties and Datatypes</a></li>

								      	  <li><a href="#PropertiesOfIndividuals">3.2.3. Properties of Individuals</a></li>

								      	</ul></li>

								      <li><a href="#PropertyCharacteristics">3.3. Property Characteristics</a></li>

								      <li><a href="#PropertyRestrictions">3.4. Property Restrictions</a>

								      	<ul>

								      	  <li><a href="#allValuesFrom">3.4.1. allValuesFrom, someValuesFrom </a></li>

								      	  <li><a href="#simpleCardinality">3.4.2. Cardinality </a></li>

								      	  <li><a href="#hasValue">3.4.3. hasValue</a></li>

								      	</ul></li>

								    </ul></li>

								  <li><a href="#OntologyMapping">4. Ontology Mapping </a>

								    <ul>

								      <li><a href="#equivalentClass1">4.1. Equivalence between Classes and Properties</a></li>

								      <li><a href="#sameAs">4.2. Identity between Individuals</a></li>

								      <li><a href="#differentFrom">4.3. 4.3. Different Individuals</a></li>

								    </ul></li>

								  <li><a href="#ComplexClasses">5. Complex Classes</a>

								    <ul>

								      <li><a href="#SetOperators">5.1. Set Operators</a></li>

								      <li><a href="#EnumeratedClasses">5.2. Enumerated Classes</a></li>

								      <li><a href="#DisjointClasses">5.3. Disjoint Classes</a></li>

								    </ul>

								  </li>

								  <li><a href="#OntologyVersioning">6. Ontology Versioning</a></li>


								  <li><a href="#Usage">7. Usage Examples</a>

								    <ul>

								      <li><a href="#WinePortal">7.1. Wine Portal</a></li>

								      <li><a href="#WineAgent">7.2. Wine Agent</a></li>

								    </ul>

								  </li>

								  <li><a href="#Acknowledgements">Acknowledgements</a></li>

								  <li><a href="#OWLGlossary">OWL Glossary</a></li>

								  <li><a href="#TermIndex">Term Index and Cross Reference</a></li>

								  <li><a href="#References">References</a></li>

								  <li><a href="#AppendixA">Appendix A: XML + RDF Basics</a></li>

								  <li><a href="#AppendixB">Appendix B: History</a></li>

								  <li><a href="#AppendixC">Appendix C: An Alternative Region Ontology</a></li>

								  <li><a href="#AppendixD">Appendix D: Change Log Since Last Call Release</a></li>

								</ul>


								<hr />


								<h1><a name="Introduction">1. Introduction</a></h1>


								<p class="quote">

								"Tell me what wines I should buy to serve with each course of the

								following menu.  And, by the way, I don't like Sauterne."</p>


								<p>

								It would be difficult today to construct a Web agent that would be

								capable of performing a search for wines on the Web that satisfied

								this query.  Similarly, consider actually assigning a software agent

								the task of making a coherent set of travel arrangements.  (For more

								use cases see the <a href="http://www.w3.org/TR/2003/CR-webont-req-20030818/">OWL

								requirements document</a>.)

								</p>


								<p>

								To support this sort of computation, it is necessary to go beyond

								keywords and specify the meaning of the resources described on

								the Web. This additional layer of interpretation captures the

								<em>semantics</em> of the data.

								</p>


								<p>

								<a id="term_ontology" name="term_ontology"></a>

								The OWL Web Ontolgoy Language is a language for defining and instantiating <em>Web

								ontologies</em>.  <em>Ontology</em> is a term borrowed from philosophy

								that refers to the science of describing the kinds of entities in the

								world and how they are related.  An

								<a name="Owl_Ontology_definition" id="Owl_Ontology_definition">

								<em>OWL ontology</em></a> may include

								descriptions of <i>classes</i>, <i>properties</i> and their instances.

								Given such an ontology, the

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/">

								OWL formal semantics</a> specifies how to derive its logical

								consequences, i.e. facts not literally present in the ontology, but

								<a id="term_entailed" name="term_entailed"></a><em>entailed</em> by the

								semantics.  These entailments may be based on

								a single document or multiple distributed documents that have been

								combined using defined <a href="#import">OWL mechanisms</a>.

								</p>


								<p>

								This document is one component of the description of OWL, the Web Ontology

								Language, being produced by the W3C Web Ontology Working Group (WebOnt).

								The <a href="http://www.w3.org/TR/2003/CR-owl-features-20030818/#s1.1">Document Roadmap</a> section

								of the Overview describes each of the different parts

								and how they fit together.

								</p>


								<p>

								One question that comes up when describing yet another XML/Web

								standard is "What does this buy me that XML and XML Schema don't?"

								<!-- An operational consensus can always be developed over the meaning of a

								set of XML tags and their contents.  There is furious ongoing

								standards activity doing exactly this.

								</p>

								<p> -->

								There are two answers to this question.

								</p>

								<ul>

								<li>

								An ontology differs from an XML schema in that it is a knowledge

								representation, not a message format.  Most industry based Web

								standards consist of a combination of message formats and protocol

								specifications.  These formats have been given an operational

								semantics, such as,  "Upon receipt of this <tt>PurchaseOrder</tt> message,

								transfer <tt>Amount</tt> dollars from <tt>AccountFrom</tt> to

								<tt>AccountTo</tt> and ship <tt>Product</tt>."  But the specification

								is not designed to support reasoning outside the transaction context.

								For example, we won't in general have a mechanism to conclude that

								because the <tt>Product</tt> is a type of Chardonnay it must also be a

								white wine.  <br /><br />

								</li>


								<li>

								One advantage of OWL ontologies will be the availability of tools that

								can reason about them.  Tools will provide <em>generic</em> support

								that is not specific to the particular subject domain, which would be

								the case if one were to build a system to reason about a specific

								industry-standard XML schema.  Building a sound and useful reasoning

								system is not a simple effort.  Constructing an ontology is much more

								tractable.  It is our expectation that many groups will embark on

								ontology construction.  They will benefit from third party tools based

								on the formal properties of the OWL language, tools that will deliver

								an assortment of capabilities that most organizations would be hard

								pressed to duplicate.  <br />

								</li>

								</ul>


								<h2><a name="OwlVarieties">1.1. The Species of OWL</a></h2>


								<p>

								The OWL language provides three increasingly expressive sublanguages

								designed for use by specific communities of implementers and users.

								</p>

								<ul>

								<li>

								<p><a id="term_OWLLite" name="term_OWLLite"></a><em>OWL Lite</em> supports those users primarily needing a classification

								  hierarchy and simple constraint features.   For example, while OWL Lite

								  supports cardinality constraints, it only permits cardinality values

								  of 0 or 1. It should be simpler to provide tool support for

								  OWL Lite than its more expressive relatives, and provide a quick migration path

								  for thesauri and other taxonomies.   </p>

								</li>


								<li>

								<p><a id="term_OWLDL" name="term_OWLDL"></a><em>OWL DL</em> supports those users

								who want the maximum expressiveness without losing computational

								completeness (all entailments are guaranteed to be computed) and decidability (all

								computations will finish in finite time) of reasoning systems.

								OWL DL includes all OWL language constructs

								with restrictions such as type separation (a class can not also be an individual or

								property, a property can not also be an individual or class).

								OWL DL is so named due to its correspondence with

								  <a href="#DescriptionLogics"><em>description logics</em></a>,

								  a field of research that has studied a particular decidable fragment of

								  first order logic.  OWL DL was designed to support the existing Description Logic

								  business segment and has desirable computational properties

								  for reasoning systems.

								</p>

								</li>


								<li>

								<p><a id="term_OWLFull" name="term_OWLFull"></a><em>OWL Full</em> is meant for

								users who want maximum expressiveness and the syntactic freedom of RDF with

								no computational guarantees.  For example, in OWL Full a class

								  can be treated simultaneously as a collection of individuals

								  and as an individual in its own right.  Another significant difference from

								  OWL DL is that a <tt>owl:DatatypeProperty</tt> can be marked as

								  an <tt>owl:InverseFunctionalProperty</tt>.  OWL Full allows an ontology to

								  augment the meaning of the pre-defined (RDF or OWL) vocabulary.  It is

								unlikely that any reasoning software will be able to support every feature of

								OWL Full.

								<!-- DELETED

								Some communities may find it useful

								to create other subsets of OWL Full than OWL DL that

								have desireable computational properties while requiring

								a different set of constraints. -->

								</p>

								</li>

								</ul>


								<p>

								Each of these sublanguages is an extension of its simpler predecessor, both

								in what can be legally expressed and in what can be validly concluded.

								The following set of relations hold. Their inverses do not.

								</p>

								<ul>

								<li>Every legal OWL Lite ontology is a legal OWL DL ontology. </li>

								<li>Every legal OWL DL ontology is a legal OWL Full ontology. </li>

								<li>Every valid OWL Lite conclusion is a valid OWL DL conclusion.</li>

								<li>Every valid OWL DL conclusion is a valid OWL Full conclusion.</li>

								</ul>


								<p>

								  Ontology developers adopting OWL should consider which species best

								  suits their needs.  The choice between OWL Lite and OWL DL

								  depends on the extent to which users require the more expressive

								  restriction constructs provided by OWL DL.  Reasoners for OWL

								  Lite will have desirable computational properties.  Reasoners for

								  OWL DL, while dealing with a decidable sublanguage, will be subject to

								  higher worst-case complexity.

								  The choice between OWL DL and OWL Full mainly

								  depends on the extent to which users require the

								  meta-modelling facilities of RDF Schema (i.e. defining classes of

								  classes).

								  When using OWL Full as compared to OWL

								  DL, reasoning support is less predictable.

								  For more information about this issue see the

								  <a href="#FormalModel">semantics document</a>.

								</p>

								<p>


								Users migrating from RDF to OWL DL or OWL Lite need to take care to

								ensure that the original RDF document complies with the constraints

								imposed by OWL DL and OWL Lite. The details of these constraints are

								explained in

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#app-DLinRDF">

								Appendix E</a> of the OWL Reference.


								</p>

								<p>

								<a name="OWL_DL_tag"></a>

								<a name="OWL_Full_tag"></a>

								When we introduce constructs that are only permitted in OWL DL or

								OWL Full, they are marked by "[OWL DL]".

								</p>


								<h2><a name="StructureOfDoc">1.2. Structure of the Document</a></h2>


								<p>

								In order to provide a consistent set of examples throughout the

								guide, we have created a <a href="wine.rdf">wine</a> and

								<a href="food.rdf">food</a> ontology.  This

								is an OWL DL ontology.  Some of our discussion will

								focus on OWL Full capabilities and is so marked.


								The wine and food ontology is a significant modification of an <a

								href="#wine1">element</a> of the DAML ontology library with a long

								history.  It was originally developed by McGuinness as a CLASSIC

								description logic <a href="#wine3">example</a>, expanded to a

								description logic <a href="#wine4">tutorial</a>, and expanded to an ontology

								<a href="#wine2">tutorial</a>.

								</p>


								<p>

								In this document we present examples using the

								<a href="http://www.w3.org/TR/REC-rdf-syntax/#grammar">RDF/XML syntax</a>,

								assuming XML will be familiar

								to the largest audience.  The normative OWL exchange syntax is RDF/XML.

								Note that OWL has been designed for maximal compatibility

								with RDF and RDF Schema.  These XML and RDF formats are part of the

								OWL standard.

								</p>


								<!--

								Notes indicating expected changes pending clarification are marked

								with '@@', e.g. [@@ Note].

								-->


								<p>

								All of the examples presented in this document are taken from the

								ontologies contained in <a href="wine.rdf">wine.rdf</a> and <a

								href="food.rdf">food.rdf</a>, except those marked with <span

								class="red">&nbsp;&not;&nbsp;</span> in the bottom right corner.

								</p>


								<hr />


								<h1><a name="StructureOfOntologies">2. The Structure of Ontologies</a>

								</h1>


								<p>

								OWL is a component of the <a

								href="http://www.w3.org/2001/sw/"><i>Semantic Web</i></a>

								activity. This effort aims to make Web resources more readily

								accessible to automated processes by adding information about the resources

								that describe or provide Web content.

								As the Semantic Web is inherently distributed, OWL must allow for information to be

								gathered from distributed sources.  This is partly done by allowing

								ontologies to be related, including explicitly importing

								information from other ontologies.

								</p>

								<p>

								In addition, OWL makes an <a id="term_openworld"

								name="term_openworld"></a><em>open world</em> assumption.  That is,

								descriptions of resources are not confined to a single file or scope.

								While class <tt>C1</tt> may be defined originally in ontology O1, it

								can be extended in other ontologies.  The consequences of these

								additional propositions about <tt>C1</tt> are <a id="term_monotonic"

								name="term_monotonic"></a><em>monotonic</em>.  New information cannot

								retract previous information.  New information can be contradictory,

								but facts and entailments can only be <em>added</em>, never

								<em>deleted</em>.

								</p>

								<p>

								The possibility of such contradictions is something the designer of an

								ontology needs to take into consideration.  It is expected that tool

								support will help detect such cases.

								</p>


								<p>

								In order to write an ontology that can be interpreted

								unambiguously and used by software agents we require a syntax and formal semantics for

								OWL.   OWL is a vocabulary extension

								<a href="http://www.w3.org/TR/rdf-mt/">[RDF Semantics]</a> of RDF.

								The OWL semantics are defined in

								<a href="#FormalModel"><i>OWL Web Ontology Language Semantics and Abstract Syntax</i></a>.

								</p>


								<h2><a name="Namespaces">2.1. Namespaces</a></h2>


								<p>

								Before we can use a set of terms, we need a precise indication of what

								specific vocabularies are being used.

								A standard initial component of an ontology includes a set of

								<a href="#XMLNS"><em>XML namespace</em></a> declarations enclosed in

								an opening <tt>rdf:RDF</tt> tag.


								These provide a means to unambiguously interpret identifiers and make

								the rest of the ontology presentation much more readable.  A typical

								OWL ontology begins with a <a href="#XMLNS">namespace declaration</a>

								similar to the following.   Of course, the URI's of the defined

								ontologies will not usually be w3.org references.

								</p>


								<pre>

								&lt;rdf:RDF

								    xmlns     ="http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#"

								    xmlns:vin ="http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#"

								    xml:base  ="http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#"

								    xmlns:food="http://www.w3.org/TR/2003/CR-owl-guide-20030818/food#"

								    xmlns:owl ="http://www.w3.org/2002/07/owl#"

								    xmlns:rdf ="http://www.w3.org/1999/02/22-rdf-syntax-ns#"

								    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"

								    xmlns:xsd ="http://www.w3.org/2000/10/XMLSchema#"&gt;

								</pre>


								<p>

								The first two declarations identify the namespace associated with this

								ontology.  The first makes it the <em>default</em> namespace, stating that

								unprefixed qualified names refer to the current

								ontology.  The second identifies the namespace of the current ontology

								with the prefix <tt>vin:</tt>. The third identifies the namespace of

								the supporting food ontology with the prefix <tt>food:</tt>.

								</p>


								<p>

								The fourth namespace declaration says that in this document, elements

								prefixed with <tt>owl:</tt> should be understood as referring to

								things drawn from the namespace called

								<code>http://www.w3.org/2002/07/owl#</code>.  This is a conventional

								OWL declaration, used to introduce the OWL vocabulary.

								</p>


								<p>

								OWL depends on constructs defined by RDF, RDFS, and XML Schema datatypes.

								In this document, the <tt>rdf:</tt> prefix refers to things drawn from

								the namespace called

								<code>http://www.w3.org/1999/02/22-rdf-syntax-ns#</code>. The next two

								namespace declarations make similar statements about the RDF Schema

								(<tt>rdfs:</tt>) and XML Schema datatype (<tt>xsd:</tt>) namespaces.

								</p>


								<p>

								As an aid to writing lengthy URLs it can often be

								useful to provide a set of entity definitions in a document type

								declaration (DOCTYPE) that precedes the ontology definitions.  The names defined by the namespace

								declarations only have significance as parts of XML tags.  Attribute

								values are <em>not</em> namespace sensitive.  But in OWL we frequently

								reference ontology identifiers using attribute values.  They can be

								written down in their fully expanded form, for

								example "http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#merlot".  Alternatively,

								abbreviations can be defined using an ENTITY definition, for example:

								</p>

								<pre>

								&lt;!DOCTYPE rdf:RDF [

								    &lt;!ENTITY vin  "http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#" &gt;

								    &lt;!ENTITY food "http://www.w3.org/TR/2003/CR-owl-guide-20030818/food#" &gt; ]&gt;

								</pre>

								<p>

								After this pair of ENTITY declarations, we could write the value

								"&amp;vin;merlot" and it would expand to

								"http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#merlot".

								</p>

								<p>

								Perhaps more importantly, the <tt>rdf:RDF</tt> namespace declarations

								can then be simplified so that changes made to the

								entity declarations will propagate through the ontology consistently.

								</p>

								<pre>

								&lt;rdf:RDF

								    xmlns     ="&amp;vin;"

								    xmlns:vin ="&amp;vin;"

								    xml:base  ="&amp;vin;"

								    xmlns:food="&amp;food;"

								    xmlns:owl ="http://www.w3.org/2002/07/owl#"

								    xmlns:rdf ="http://www.w3.org/1999/02/22-rdf-syntax-ns#"

								    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"

								    xmlns:xsd ="http://www.w3.org/2000/10/XMLSchema#"&gt;

								</pre>


								<h2><a name="OntologyHeaders" id="OntologyHeaders">2.2. Ontology Headers</a></h2>


								<p><a id="owl_Ontology" name="owl_Ontology"></a>

								Once namespaces are established we normally include a

								collection of  assertions about the ontology grouped under

								an <tt>owl:Ontology</tt> tag.  These tags support

								such critical housekeeping tasks as comments, version control and

								inclusion of other ontologies.

								</p>


								<pre>

								&lt;owl:Ontology rdf:about=""&gt;

								  &lt;rdfs:comment&gt;An example OWL ontology&lt;/rdfs:comment&gt;

								  &lt;owl:priorVersion rdf:resource="http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine"/&gt;

								  &lt;owl:imports rdf:resource="http://www.w3.org/TR/2003/CR-owl-guide-20030818/food"/&gt;

								  &lt;rdfs:label&gt;Wine Ontology&lt;/rdfs:label&gt;

								  ...

								</pre>


								<p>

								Note that we use '...' to indicate that there is additional text that

								has been elided for purposes of the example.

								</p>


								<p>

								The <tt>owl:Ontology</tt> element is a place to collect much of

								the OWL meta-data for the document.  It does not guarantee that the

								document describes an ontology in the traditional sense.

								In some communities, ontologies

								are not about individuals but only the classes and properties that define a domain.

								When using OWL to describe a collection of instance data

								the <tt>owl:Ontology</tt> tag may be needed in order to record version

								information and to import the definitions that the document depends on.

								Thus, in OWL the term <em>ontology</em> has been broadened to include

								instance data (<a href="#Owl_Ontology_definition">see above</a>).

								</p>


								<p>

								<a id="owl_imports" name="owl_imports"></a>

								<a id="rdfs_comment" name="rdfs_comment"></a>

								The <tt>rdf:about</tt> attribute provides a name or reference for the ontology.

								Where the value of the attribute is "", the standard case, the

								name of the ontology is the base URI of the <tt>owl:Ontology</tt> element.

								Typically, this is the URI of the document containing the ontology.

								An exception to this is a context that makes use of <tt>xml:base</tt>

								which may set the base URI for an element to something other than the

								URI of the current document.

								</p>


								<p>

								<tt>rdfs:comment</tt> provides the obvious needed capability

								to annotate an ontology.

								</p>


								<p>

								<tt>owl:priorVersion</tt> is a standard tag intended to provide

								hooks for version control systems working with ontologies.  Ontology

								versioning is discussed further <a href="#OntologyVersioning">below.</a>

								</p>


								<p>

								<a name="term_import" id="term_import"></a>

								<a name="import" id="import"><tt>owl:imports</tt></a>

								provides an include-style mechanism.

								<tt>owl:imports</tt>

								takes a single argument, identified by the <tt>rdf:resource</tt> attribute.

								</p>


								<p>

								Importing another ontology brings the entire set of assertions

								provided by that ontology into the current ontology.

								In order to make best use of this imported ontology it would normally

								be coordinated with a namespace declaration.  Notice the distinction

								between these two mechanisms.  The namespace declarations provide

								a convenient means to <em>reference</em> names defined in other OWL

								ontologies.


								Conceptually, <tt>owl:imports</tt> is provided to indicate your

								intention to <em>include</em> the assertions of the target ontology.

								Importing another ontology, <em>O2</em>, will also import all of the

								ontologies that <em>O2</em> imports.

								</p>


								<p>

								Note that <tt>owl:imports</tt> may not always succeed.  As you would

								expect when dealing with the Semantic Web, access to resources

								distributed across the Web may not always be possible.  Tools will

								respond to this situation in an implementation defined manner.

								</p>


								<p>

								Note that in order to use the OWL vocabulary you do not need to

								import the <a href="http://www.w3.org/2002/07/owl">owl.rdf</a>

								ontology.  In fact, such an import is not recommended.

								</p>


								<p>

								One common set of additional tags that could reasonably be included

								here are some of the standard <a href="#DublinCore">Dublin

								Core</a> metadata tags.  The subset includes those that take simple

								types or strings as values.  Examples include Title, Creator,

								Description, Publisher, and Date (see

								<a href="http://purl.org/dc/elements/1.1/">RDF declarations</a>).

								</p>


								<p>

								Properties that are used as annotations should be declared using

								<tt>owl:AnnotationProperty</tt>.  E.g.

								</p>

								<pre>

								&lt;owl:AnnotationProperty rdf:about="&amp;dc;creator" /&gt;

								</pre>


								<p>

								OWL provides several other mechanisms to tie the current ontology and

								imported ontologies together (see <a href="#OntologyMapping">ontology

								mapping</a>).

								</p>

								<p>

								We also include an <tt>rdfs:label</tt> to

								support a natural language label for our ontology.

								</p>


								<p>The ontology header definition is closed with

								the following tag.

								</p>

								<pre>

								&lt;/owl:Ontology&gt;

								</pre>

								<p>

								This prelude is followed by the actual definitions that

								make up the ontology and is ultimately closed by

								</p>

								<pre>

								&lt;/rdf:RDF&gt;

								</pre>


								<h2><a id="Privacy" name="Privacy">2.3. Data Aggregation and Privacy</a></h2>


								<p>

								OWL's ability to express ontological information about instances

								appearing in multiple documents supports linking of data from diverse

								sources in a principled way.  The underlying semantics provides

								support for inferences over this data that may yield unexpected

								results.  In particular, the ability to express equivalences using

								<tt>owl:sameAs</tt> can be used to state that seemingly

								different individuals are actually the same.

								<tt>Owl:InverseFunctionalProperty</tt> can also be used to link

								individuals together.

								For example, if a property such as "SocialSecurityNumber" is an

								<tt>owl:InverseFunctionalProperty</tt>, then two separate individuals

								could be inferred to be identical based on having the same value of

								that property.  When individuals are determined to be the same by such

								means, information about them from different sources can be

								merged. This <i>aggregation</i> can be used to determine facts that

								are not <i>directly</i> represented in any one source.

								</p>


								<p>

								The ability of the Semantic Web to link information from multiple

								sources is a desirable and powerful feature that can be used in many

								<a href="#IntegratingApplications">applications</a>.

								However, the capability to merge data from multiple sources, combined

								with the inferential power of OWL, does have potential for abuse.

								Users of OWL should be alert to the potential privacy implications.


								Detailed security solutions were considered out of scope for the

								Workng Group.  A number of organizations are addressing these

								issues with a variety of security and preference solutions.

								See for example

								<a href="http://www.oasis-open.org/committees/security/charter.php">

								SAML</a> and

								<a href="http://www.w3.org/P3P/">P3P</a>.

								</p>


								<hr />


								<h1><a name="BasicDefinitions">3. Basic Elements</a></h1>


								<p>

								Most of the elements of an OWL ontology concern classes, properties,

								instances of classes, and relationships between these instances.

								This section presents the language components essential to introducing

								these elements.

								</p>


								<h2><a name="SimpleClasses">3.1. Simple Classes and Individuals</a></h2>


								<p>

								Many uses of an ontology will depend on the ability to reason

								about individuals.  In order to do this in a useful fashion we need to

								have a mechanism to describe the classes that individuals belong to

								and the properties that they inherit by virtue of class membership.

								We can always assert specific properties about individuals, but much

								of the power of ontologies comes from class-based reasoning.

								</p>

								<p>

								Sometimes we want to emphasize the distinction between a class as an

								object and a class as a set containing elements.

								We call the set of individuals that are members of a class

								the <a id="term_extension" name="term_extension"></a><em>extension</em> of the class.

								</p>


								<h3><a name="DefiningSimpleClasses">3.1.1. Simple Named Classes</a><br />

								<tt>Class, rdfs:subClassOf</tt></h3>


								<p>

								<a id="owl_Thing" name="owl_Thing"></a>

								<a id="owl_Nothing" name="owl_Nothing"></a>

								The most basic concepts in a domain should correspond

								to classes that are the roots of various

								taxonomic trees.  Every individual in the OWL world is a member of

								the class

								<tt>owl:Thing</tt>.  Thus each user-defined class

								is implicitly a subclass of <tt>owl:Thing</tt>.  Domain specific root classes are

								defined by simply declaring a named class.

								OWL also defines the empty class, <tt>owl:Nothing</tt>.

								</p>


								<p><a id="owl_Class" name="owl_Class"></a>

								For our sample wines domain, we create three root classes: <tt>Winery</tt>,

								<tt>Region</tt>, and <tt>ConsumableThing</tt>.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Winery"/&gt;

								&lt;owl:Class rdf:ID="Region"/&gt;

								&lt;owl:Class rdf:ID="ConsumableThing"/&gt;

								</pre>


								<p>

								Note that we have only said that there exist classes that have been

								given these names, indicated by the '<tt>rdf:ID=</tt>' syntax.  Formally, we

								know almost nothing about these classes other than their existence,

								despite the use of familiar English terms as labels.  And while the

								classes exist, they may have no members.  For all we know at the

								moment, these classes might as well have been called <tt>Thing1</tt>,

								<tt>Thing2</tt>, and <tt>Thing3</tt>.

								</p>

								<p>

								It is important to remember that definitions may be incremental and distributed.

								In particular, we will have more to say about <tt>Winery</tt> later.

								</p>


								<p>

								The syntax <tt>rdf:ID="Region"</tt> is used to introduce a

								name, as part of its definition. This is the

								<a href="http://www.w3.org/TR/rdf-syntax-grammar/#idAttr">rdf:ID</a>

								attribute that is like the familiar ID attribute defined by XML.

								Within this document, the <tt>Region</tt> class can now be referred to using

								<tt>rdf:resource="#Region"</tt>.  Other ontologies may reference this

								name using its complete form,

								<tt>"http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#Region"</tt>.

								</p>


								<p>

								Another form of reference

								uses the syntax <tt>rdf:about="#Region"</tt> to <a

								href="#DefiningIndividuals"><em>extend</em></a> the definition of a

								resource.

								This use of the <tt>rdf:about="#x"</tt> syntax is a critical element

								in the creation of a distributed ontology.  It permits the extension

								of the imported definition of <tt>x</tt> without modifying the

								original document and supports the incremental construction of a larger ontology.

								</p>

								<p>

								It is now possible to refer to the classes we defined in other OWL

								constructs using their given identifier.  For the first class, within

								this document, we can use the relative identifier, <tt>#Winery</tt>.

								Other documents may need to reference this class as well.  The most

								reasonable way to do so is to provide namespace and entity definitions

								that include the defining document as a source:

								</p>

								<pre>

								...

								&lt;!ENTITY vin  "http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#" &gt;

								&lt;!ENTITY food "http://www.w3.org/TR/2003/CR-owl-guide-20030818/food#" &gt;

								...

								&lt;rdf:RDF xmlns:vin ="http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#"

								         xmlns:food="http://www.w3.org/TR/2003/CR-owl-guide-20030818/food#" ... &gt;

								...

								</pre>

								<p>

								Given these definitions we can refer to the winery class either

								using the XML tag <tt>vin:Winery</tt> or the attribute value <tt>&amp;vin;Winery</tt>.

								More literally, it is always possible to reference a resource using its full URI,

								here <code>http://www.w3.org/TR/2003/CR-owl-guide-20030818/wine#Winery</code>.

								</p>


								<p>

								The fundamental taxonomic constructor for

								classes is <tt>rdfs:subClassOf</tt>.

								It relates a more specific class to a more general

								class.  If X is a subclass of Y, then every instance of X is also

								an instance of Y.

								The <tt>rdfs:subClsssOf</tt> relation is transitive.  If X is a subclass of Y

								and Y a subclass of Z then X is a subclass of Z.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="PotableLiquid"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#ConsumableThing" /&gt;

								  ...

								&lt;/owl:Class&gt;

								</pre>


								<p>

								We define <tt>PotableLiquid</tt> (liquids suitable for drinking) to

								be a subclass of <tt>ConsumableThing</tt>.

								</p>

								<p>

								In the world of Web-based ontologies, both of these classes

								can be defined in a separate ontology that would provide the basic

								building blocks for a wide variety of food and drink ontologies, which

								is what we have done - they are defined in the

								<a href="food.rdf">food</a> ontology, which

								is <a href="#import">imported</a> into the wine ontology.

								The food ontology includes a number of classes, for example

								<tt>Food</tt>, <tt>EdibleThing</tt>, <tt>MealCourse</tt>, and

								<tt>Shellfish</tt>, that do not belong in a collection of wine facts,

								but must be connected to the wine vocabulary if we are going to

								perform useful reasoning.  Food and wine are mutually

								dependent, in order to satisfy our need to identify wine/food matches.

								</p>


								<p>

								A class definition has two parts: a name introduction or reference

								and a list of restrictions.  Each of the immediate contained

								expressions in the class definition further restricts the instances of

								the defined class.  Instances of the class belong to the intersection of

								the restrictions.  (Though see the details of <a href="#owl_equivalentClass">

								<tt>owl:equivalentClass</tt></a>.)

								So far we have only seen examples that include a single restriction,

								forcing the new class to be a subclass of some other named class.

								</p>


								<p>

								<a id="rdfs_subClassOf" name="rdfs_subClassOf"></a>

								<a id="rdfs_label" name="rdfs_label"></a>

								At this point it is possible to create a simple (and incomplete)

								definition for the class <tt>Wine</tt>.  <tt>Wine</tt> is a

								<tt>PotableLiquid</tt>.  We also define <tt>Pasta</tt> as an

								<tt>EdibleThing</tt>.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Wine"&gt;

								  &lt;rdfs:subClassOf rdf:resource="&amp;food;PotableLiquid"/&gt;

								  &lt;rdfs:label xml:lang="en"&gt;wine&lt;/rdfs:label&gt;

								  &lt;rdfs:label xml:lang="fr"&gt;vin&lt;/rdfs:label&gt;

								  ...

								&lt;/owl:Class&gt;


								&lt;owl:Class rdf:ID="Pasta"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#EdibleThing" /&gt;

								  ...

								&lt;/owl:Class&gt;

								</pre>


								<p>

								The <tt>rdfs:label</tt> entry provides an optional human readable

								name for this class.  Presentation tools can make use of it.

								The "lang" attribute provides support for multiple languages.  A label

								is like a comment and contributes nothing to the logical

								interpretation of an ontology. </p>


								<p>

								Our wine definition is still very incomplete. We know nothing about

								wines except that they are things and potable liquids, but we have

								sufficient information to create and reason about individuals.

								</p>


								<h3><a name="DefiningIndividuals">3.1.2. Individuals</a></h3>


								<p>

								In addition to classes, we want to be able to describe their members.

								We normally think of these as individuals in our universe of things.

								An individual is minimally introduced by declaring it to be a member

								of a class.

								</p>

								<pre>

								&lt;Region rdf:ID="CentralCoastRegion" /&gt;

								</pre>


								<p>

								Note that the following is identical in meaning to the

								example above.

								<a id="rdf_type" name="rdf_type"></a>

								</p>


								<pre>

								&lt;owl:Thing rdf:ID="CentralCoastRegion" /&gt;


								&lt;owl:Thing rdf:about="#CentralCoastRegion"&gt;

								   &lt;rdf:type rdf:resource="#Region"/&gt;

								&lt;/owl:Thing&gt;

								</pre>


								<p>

								<tt>rdf:type</tt> is an RDF property that ties an individual to a class

								   of which it is a member.

								</p>


								<p>

								There are a couple of points to be made here. First,

								we have decided that <tt>CentralCoastRegion</tt> (a specific area) is

								member of <tt>Region</tt>, the class containing all geographical regions.

								Second, there is no requirement in the two-part example that the two

								elements need to be adjacent to one another, or even in the same

								file (though the names would need to be extended with a URI in such a

								case).  We design Web ontologies to be distributed.  They can be

								imported and augmented, creating derived ontologies.

								</p>


								<p>

								In order to have available a few more classes for the

								properties introduced in the next sections, we define a branch

								of the <tt>Grape</tt> taxonomy, with an individual denoting the

								Cabernet Sauvignon grape varietal.  Grapes are defined in the food ontology:

								</p>

								<pre>

								&lt;owl:Class rdf:ID="Grape"&gt;

								  ...

								&lt;/owl:Class&gt;

								</pre>

								<p>

								And then in the wine ontology we have:

								</p>

								<pre>

								&lt;owl:Class rdf:ID="WineGrape"&gt;

								  &lt;rdfs:subClassOf rdf:resource="&amp;food;Grape" /&gt;

								&lt;/owl:Class&gt;


								&lt;WineGrape rdf:ID="CabernetSauvignonGrape" /&gt;

								</pre>


								<p>

								<!-- this means that we have in some sense limited our ontology

								for specific purposes.  Because it is itself an individual,

								we cannot create an instance of <tt>CabernetSauvignonGrape</tt>.

								If we needed to talk about individual grapes or specific bunches of grapes, we would have

								designed the ontology differently. -->


								As discussed in the next section,

								<tt>CabernetSauvignonGrape</tt> is an individual because it denotes a

								single grape varietal.

								</p>


								<h3><a name="DesignForUse">3.1.3. Design for Use</a></h3>


								<p>

								<a id="term_class" name="term_class"></a>

								<a id="term_individual" name="term_individual"></a>

								There are important issues regarding the distinction between a <i>class</i> and

								an <i>individual</i> in OWL.  A class is simply a name and collection of properties

								that describe a set of individuals. Individuals are the members of those sets.

								Thus classes should correspond to naturally occurring sets of things in a domain

								of discourse, and individuals should correspond to actual entities that can be grouped

								into these classes.

								</p>

								<p>

								In building ontologies, this distinction is frequently blurred in two ways:

								</p>


								<ul>

								  <li>

								  <i>Levels of representation:</i> It is well known that in certain contexts something

								  that is obviously a class can itself be considered an instance of something else.  For

								  example, in the wine ontology we have the notion of a <tt>Grape</tt>, which is

								  intended to denote the set of all <i>grape varietals.</i>

								  <tt>CabernetSauvingonGrape</tt> is

								  an example instance of this class, as it denotes the actual grape varietal

								  called Cabernet Sauvignon.

								  However, <tt>CabernetSauvignonGrape</tt> could itself be considered a class, the set of all

								  actual Cabernet Sauvignon grapes.

								  <br />

								  <br />

								</li>


								<li>

								<a id="instance-of" name="instance-of"></a>

								<a id="term_instanceOf" name="term_instanceOf"></a>

								<i>Subclass vs. instance:</i> It is very easy to confuse the

								instance-of relationship with the subclass relationship.

								For example, it may seem arbitrary to choose to make <tt>CabernetSauvignonGrape</tt>

								an individual that is an instance of <tt>Grape,</tt> as opposed to a subclass of <tt>Grape</tt>.

								This is not an arbitrary

								decision.  The <tt>Grape</tt>  class denotes the set of all

								<i>grape varietals</i>, and therefore any subclass of <tt>Grape</tt>  should denote a subset of these

								varietals. Thus, CabernetSauvignonGrape should be considered an

								<a id="term_instance" name="term_instance"></a><em>instance of</em> Grape, and not a subclass. It does not

								describe a subset of Grape varietals, it <em>is</em> a grape varietal.

								</li>

								</ul>


								<p>

								Note that the same distinction arises with the treatment of the

								<tt>Wine</tt> class.  The <tt>Wine</tt> class actually denotes the set

								of all <em>varieties</em> of wine, not the set of actual bottles that

								someone may purchase.


								Each instance of <tt>Wine</tt> could be considered the class

								consisting of all the bottles of wine of that type.  It is easy to

								imagine an information system, such as an inventory system for a wine

								merchant, that needs to consider individual bottles of wine.


								The wine ontology as it currently exists would require the ability to

								treat classes as instances in order to support such an interpretation.


								Note that OWL Full permits such expressivity,

								allowing us to treat an instance of a wine variety simultaneously

								as a class whose instances are bottles of wine.


								</p>


								<p>

								In a similar vein, the wines produced by wineries in specific years

								are considered vintages.  In order to represent the notion of a

								vintage, we must determine where it fits in the current ontology.  An

								instance of the <tt>Wine</tt> class, as discussed above, represents a

								single variety of wine produced by a single winery, for example

								<tt>FormanChardonnay.</tt>

								</p>


								<p>

								Adding that the wine produced in the year 2000 is considered a

								<a id="vintageIntro" name="vintageIntro">vintage</a>

								poses a challenge, because we don't have the ability to represent a

								subset of a given wine individual.  This vintage is not a new

								variety of wine, it is a special subset of the wine - that produced in

								the year 2000.


								An option would be to use OWL Full and treat the wine instances as

								classes with subclasses (subsets) denoting vintages. Another option is

								to use a workaround and to consider <tt>Vintage</tt> as a separate class whose

								instances have a relationship to the Wine they are a vintage of.


								For example, <tt>FormanChardonnay2000</tt> is an

								individual <tt>Vintage</tt> with a <tt>vintageOf</tt> property whose value is

								the <tt>Wine</tt>, <tt>FormanChardonnay.</tt> We define the

								<a href="#vintage"><tt>Vintage</tt></a> class below.

								</p>


								<p>

								The point of this

								discussion is to note that the development of an ontology should be

								firmly driven by the intended usage.  These issues also underlie

								one major difference between OWL Full and OWL DL. OWL Full

								allows the use of classes as instances and OWL DL does not.

								The wine ontology is designed to work in OWL DL, and

								as a result individuals like <tt>FormanChardonnay</tt> are not

								simultaneously treated as classes.

								</p>


								<h2><a name="SimpleProperties">3.2. Simple Properties </a></h2>


								<p>This world of classes and individuals would be pretty uninteresting

								if we could only define taxonomies.

								<a id="term_Properties" name="term_Properties"></a><em>Properties</em> let us assert

								general facts about the members of classes and specific facts about

								individuals.

								</p>


								<h3><a name="DefiningProperties">3.2.1. Defining Properties</a><br />

								<tt>ObjectProperty, DatatypeProperty, rdfs:subPropertyOf, <br />

								rdfs:domain, rdfs:range</tt></h3>


								<p>A property is a binary relation.

								Two types of properties are distinguished:

								</p>


								<ul>

								<li>

								<a id="term_datatypeproperties" name="term_datatypeproperties"></a><em>datatype properties</em>,

								relations between instances of

								classes and RDF literals and XML Schema datatypes</li>


								<li><a id="term_objectproperties" name="term_objectproperties"></a><em>object properties</em>,

								relations between instances of two classes.

								Note that the name <i>object</i> property is not intended to reflect a

								connection with the <a href="http://www.w3.org/RDF/">RDF</a> term <a

								href="http://www.w3.org/TR/rdf-schema/#ch_object">rdf:object</a>.

								</li>

								</ul>


								<p>

								<a id="owl_ObjectProperty" name="owl_ObjectProperty"></a>

								<a id="term_domain" name="term_domain"></a>

								<a id="term_range" name="term_range"></a>

								<a id="rdfs_domain" name="rdfs_domain"></a>

								<a id="rdfs_range" name="rdfs_range"></a>

								When we define a property

								there are a number of ways to restrict the relation.

								The domain and range can be specified.  The property can be defined to

								be a specialization (subproperty) of an existing property.  More elaborate

								restrictions are possible and are described

								<a href="#PropertyCharacteristics">later</a>.

								</p>


								<pre>

								&lt;owl:ObjectProperty rdf:ID="madeFromGrape"&gt;

								  &lt;rdfs:domain rdf:resource="#Wine"/&gt;

								  &lt;rdfs:range rdf:resource="#WineGrape"/&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="course"&gt;

								  &lt;rdfs:domain rdf:resource="#Meal" /&gt;

								  &lt;rdfs:range rdf:resource="#MealCourse" /&gt;

								&lt;/owl:ObjectProperty&gt;

								</pre>


								<p>

								<a id="rdfs_subPropertyOf" name="rdfs_subPropertyOf"></a>

								In OWL, a sequence of elements without an explicit operator

								represents an implicit conjunction.

								The property <tt>madeFromGrape</tt> has a domain of <tt>Wine</tt>

								<em>and</em> a range of <tt>WineGrape</tt>.  That is, it relates

								instances of the class <tt>Wine</tt> to instances of the class

								<tt>WineGrape</tt>.   Multiple domains mean that the

								domain of the property is the intersection of

								the identified classes (and similarly for range).

								</p>

								<p>

								Similarly, the property <tt>course</tt> ties a <tt>Meal</tt> to a <tt>MealCourse</tt>.

								</p>

								<p>

								Note that the use of range and domain information in OWL is different

								from type information in a programming language.  Among other things, types

								are used to check consistency in a programming language.  In OWL, a range may be

								used to infer a type.  For example, given:

								</p>

								<pre>

								&lt;owl:Thing rdf:ID="LindemansBin65Chardonnay"&gt;

								  &lt;madeFromGrape rdf:resource="#ChardonnayGrape" /&gt;

								&lt;/owl:Thing&gt;                                             <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>

								<p>

								we can infer that <tt>LindemansBin65Chardonnay</tt> is a wine because

								the domain of <tt>madeFromGrape</tt> is <tt>Wine</tt>.

								</p>

								<p>

								Properties, like classes, can be arranged in a hierarchy.

								</p>

								<pre>

								&lt;owl:Class rdf:ID="WineDescriptor" /&gt;


								&lt;owl:Class rdf:ID="WineColor"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#WineDescriptor" /&gt;

								  ...

								&lt;/owl:Class&gt;


								&lt;owl:ObjectProperty rdf:ID="hasWineDescriptor"&gt;

								  &lt;rdfs:domain rdf:resource="#Wine" /&gt;

								  &lt;rdfs:range  rdf:resource="#WineDescriptor" /&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="hasColor"&gt;

								  &lt;rdfs:subPropertyOf rdf:resource="#hasWineDescriptor" /&gt;

								  &lt;rdfs:range rdf:resource="#WineColor" /&gt;

								  ...

								&lt;/owl:ObjectProperty&gt;

								</pre>

								<p>

								<tt>WineDescriptor</tt> properties relate wines to their color and components of their

								taste, including sweetness, body, and flavor.  <tt>hasColor</tt>  is a

								subproperty of the <tt>hasWineDescriptor</tt> property, with its range

								further restricted to <tt>WineColor</tt>.  The <tt>rdfs:subPropertyOf</tt>

								relation in this case means that anything with a <tt>hasColor</tt>

								property with value X also has a <tt>hasWineDescriptor</tt> property

								with value X.

								</p>


								<p>

								Next we introduce the <tt>locatedIn</tt> property, which relates things to

								the regions they are located in.

								</p>

								<pre>

								&lt;owl:ObjectProperty rdf:ID="locatedIn"&gt;

								  ...

								  &lt;rdfs:domain rdf:resource="http://www.w3.org/2002/07/owl#Thing" /&gt;

								  &lt;rdfs:range rdf:resource="#Region" /&gt;

								&lt;/owl:ObjectProperty&gt;

								</pre>

								<p>

								Notice how the domain and range of <tt>locatedIn</tt> are defined.

								The domain permits anything to be located in a region, including

								regions themselves.  And the <a href="#owl_TransitiveProperty

								">transitive</a>

								composition of this relation

								essentially creates a network of geographically included subregions

								and things.  Those things that have nothing located in them

								can be of any class, while those that contain others must be

								regions.

								</p>


								<p>

								It is now possible to expand the definition of <tt>Wine</tt> to

								include the notion of regions, and that a wine is

								made from at least one <tt>WineGrape</tt>.

								As with property definitions, class definitions have multiple subparts that are

								implicitly conjoined.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Wine"&gt;

								  &lt;rdfs:subClassOf rdf:resource="&amp;food;PotableLiquid"/&gt;

								  &lt;rdfs:subClassOf&gt;

								<span class="highlight">    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#madeFromGrape"/&gt;

								      &lt;owl:minCardinality rdf:datatype="&amp;xsd;nonNegativeInteger"&gt;1&lt;/owl:minCardinality&gt;

								    &lt;/owl:Restriction&gt; </span>

								  &lt;/rdfs:subClassOf&gt;

								  ...

								&lt;/owl:Class&gt;

								</pre>

								<p>

								The highlighted subclass restriction above

								</p>

								<pre>

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#madeFromGrape"/&gt;

								      &lt;owl:minCardinality rdf:datatype="&amp;xsd;nonNegativeInteger"&gt;1&lt;/owl:minCardinality&gt;

								    &lt;/owl:Restriction&gt;

								</pre>

								<p>

								defines an unnamed class that represents the set of things

								with at least one <tt>madeFromGrape</tt> property.

								We call these <a id="term_anonymousClass" name="term_anonymousClass"></a><em>anonymous</em>

								classes.  Including this restriction in the <tt>Wine</tt>

								class definition body states that things that are wines are also

								members of this anonymous class.  That is, every individual wine must participate

								in at least one <tt>madeFromGrape</tt> relation.

								</p>


								<p>

								<a name="vintage" id="vintage"/>

								We can now describe the class of <tt>Vintage</tt>s, discussed <a href="#vintageIntro">previously</a>.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Vintage"&gt;

								  &lt;rdfs:subClassOf&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#vintageOf"/&gt;

								      &lt;owl:minCardinality rdf:datatype="&amp;xsd;nonNegativeInteger"&gt;1&lt;/owl:minCardinality&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/rdfs:subClassOf&gt;

								&lt;/owl:Class&gt;                                             <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>


								<p>

								The property <tt>vintageOf</tt> ties a <tt>Vintage</tt> to a

								<tt>Wine</tt>.

								</p>


								<pre>

								&lt;owl:ObjectProperty rdf:ID="vintageOf"&gt;

								  &lt;rdfs:domain rdf:resource="#Vintage" /&gt;

								  &lt;rdfs:range  rdf:resource="#Wine" /&gt;

								&lt;/owl:ObjectProperty&gt;                                    <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>

								<p>

								We relate <tt>Vintage</tt>s to their years in the next section.

								</p>


								<h3><a name="rdfs_Datatype"></a>

								<a id="term_datatype" name="term_datatype"></a>

								<a name="Datatypes1">3.2.2. Properties and Datatypes</a></h3>


								<p>

								We distinguish

								properties according to whether they relate individuals to individuals

								(object properties) or individuals to datatypes (datatype properties).

								Datatype properties may range over strings or they may make use of

								simple types defined in accordance with

								<a href="http://www.w3.org/TR/xmlschema-2/">XML Schema datatypes</a>.

								</p>


								<p>

								<a id="owl_DatatypeProperty" name="owl_DatatypeProperty"></a>

								OWL uses some of many of the built-in XML

								Schema datatypes.  References to these datatypes are by

								means of the URI reference for the datatype,

								<tt>http://www.w3.org/2001/XMLSchema</tt>. The following datatypes are

								<em>recommended</em> for use with OWL:

								</p>


								<table class="info">

								<tr><td>xsd:string</td><td>xsd:normalizedString</td><td>xsd:boolean</td></tr>

								<tr><td>xsd:decimal</td><td>xsd:float</td><td>xsd:double</td></tr>

								<tr><td>xsd:integer</td><td>xsd:nonNegativeInteger</td><td>xsd:positiveInteger</td></tr>

								<tr><td>xsd:nonPositiveInteger</td><td>xsd:negativeInteger</td></tr>


								<tr><td>xsd:long</td><td>xsd:int</td><td>xsd:short</td><td>xsd:byte</td></tr>

								<tr><td>xsd:unsignedLong</td><td>xsd:unsignedInt</td><td>xsd:unsignedShort</td><td>xsd:unsignedByte</td></tr>

								<tr><td>xsd:hexBinary</td><td>xsd:base64Binary</td></tr>

								<tr><td>xsd:dateTime</td><td>xsd:time</td><td>xsd:date</td><td>xsd:gYearMonth</td></tr>

								<tr><td>xsd:gYear</td><td>xsd:gMonthDay</td><td>xsd:gDay</td><td>xsd:gMonth</td></tr>

								<tr><td>xsd:anyURI</td><td>xsd:token</td><td>xsd:language</td></tr>

								<tr><td>xsd:NMTOKEN</td><td>xsd:Name</td><td>xsd:NCName</td></tr>

								</table>

								<p>

								The above datatypes, plus <tt>rdfs:Literal</tt>, form the built-in OWL datatypes.

								All OWL reasoners are required to support the <tt>xsd:integer</tt>

								and <tt>xsd:string</tt> datatypes.

								</p>


								<p>

								Other built-in XML Schema datatypes may

								be used in OWL Full, but with caveats described in the

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/syntax.html">

								OWL Semantics and Abstract Syntax</a> documentation.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="VintageYear" /&gt;


								&lt;owl:DatatypeProperty rdf:ID="yearValue"&gt;

								  &lt;rdfs:domain rdf:resource="#VintageYear" /&gt;

								  &lt;rdfs:range  rdf:resource="&amp;xsd;positiveInteger"/&gt;

								&lt;/owl:DatatypeProperty&gt;

								</pre>


								<p>

								The <tt>yearValue</tt> property relates <tt>VintageYear</tt>s to positive

								integer values.

								We introduce the <tt>hasVintageYear</tt> property, which relates a <tt>Vintage</tt> to a

								<tt>VintageYear</tt> <a href="#FunctionalProperty">below.</a>

								</p>


								<p>

								The <a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#EnumeratedDatatype">

								OWL Reference</a> describes the use of <tt>owl:oneOf</tt> and

								<tt>rdf:List</tt> and <tt>rdf:rest</tt> to define an enumerated

								datatype.  The example shows how to construct the <tt>owl:DatatypeProperty</tt>,

								<tt>tennisGameScore</tt>, with a range equal to the elements of the list of integer

								values {0, 15, 30, 40}.

								</p>


								<h3><a name="PropertiesOfIndividuals">3.2.3. Properties of Individuals</a></h3>


								<p>

								First we describe <tt>Region</tt> and <tt>Winery</tt> individuals, and then

								we define our first wine, a Cabernet Sauvignon.

								</p>


								<pre>

								&lt;Region rdf:ID="SantaCruzMountainsRegion"&gt;

								  &lt;locatedIn rdf:resource="#CaliforniaRegion" /&gt;

								&lt;/Region&gt;


								&lt;Winery rdf:ID="SantaCruzMountainVineyard" /&gt;


								&lt;CabernetSauvignon rdf:ID="SantaCruzMountainVineyardCabernetSauvignon" &gt;<a name="CabernetSauvignon" id="CabernetSauvignon"/>

								  &lt;locatedIn   rdf:resource="#SantaCruzMountainsRegion"/&gt;

								  &lt;hasMaker    rdf:resource="#SantaCruzMountainVineyard" /&gt;

								&lt;/CabernetSauvignon&gt;

								</pre>


								<p>

								This is still incomplete.  There are other aspects of the wine flavor

								that are defined in the full ontology.  But the pieces are falling

								together.  We could begin reasoning about what menu items in our food

								ontology this wine might

								accompany.  We know from the definition above that the Santa Cruz

								Mountain Vineyard makes it.

								Because it is a Cabernet Sauvignon (see <a href="wine.rdf">wine.rdf</a>),

								we know it is a dry, red wine.

								</p>


								<p>

								Datatype properties can be added to individuals in a similar

								fashion. Below we describe an instance of <tt>VintageYear</tt> and tie it to a

								specific value of type <tt>xdt:positiveInteger</tt>.

								</p>


								<pre>

								&lt;VintageYear rdf:ID="Year1998"&gt;

								  &lt;yearValue rdf:datatype="&amp;xsd;positiveInteger"&gt;1998&lt;/yearValue&gt;

								&lt;/VintageYear&gt;

								</pre>


								<h2><a name="PropertyCharacteristics" id="PropertyCharacteristics">

								3.3. Property Characteristics</a></h2>


								<p>

								The next few sections describe the mechanisms used to further specify

								properties.  It is possible to specify property

								<a id="term_characteristics" name="term_characteristics"></a><em>characteristics</em>, which provides a powerful mechanism for enhanced

								reasoning about a property.

								</p>


								<dl>

								<dt><a name="TransitiveProperty">TransitiveProperty</a></dt>

								<dd>


								<p>

								<a id="owl_TransitiveProperty" name="owl_TransitiveProperty"></a>

								If a property, P, is specified as transitive then for any x, y, and z:

								</p>


								<pre>

								P(x,y) and P(y,z) implies P(x,z)

								</pre>


								<p>

								The property <tt>locatedIn</tt> is transitive.

								</p>


								<pre>

								&lt;owl:ObjectProperty rdf:ID="locatedIn"&gt;

								  &lt;rdf:type rdf:resource="&amp;owl;TransitiveProperty" /&gt;

								  &lt;rdfs:domain rdf:resource="&amp;owl;Thing" /&gt;

								  &lt;rdfs:range rdf:resource="#Region" /&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;Region rdf:ID="SantaCruzMountainsRegion"&gt;

								  &lt;locatedIn rdf:resource="#CaliforniaRegion" /&gt;

								&lt;/Region&gt;


								&lt;Region rdf:ID="CaliforniaRegion"&gt;

								  &lt;locatedIn rdf:resource="#USRegion" /&gt;

								&lt;/Region&gt;

								</pre>


								<p>

								Because the <tt>SantaCruzMountainsRegion</tt> is <tt>locatedIn</tt> the

								<tt>CaliforniaRegion</tt>, then it must also be <tt>locatedIn</tt> the

								<tt>USRegion</tt>, since <tt>locatedIn</tt> is transitive.

								</p>


								</dd>


								<dt><a name="SymmetricProperty">SymmetricProperty</a></dt>


								<dd>

								<p><a id="owl_SymmetricProperty" name="owl_SymmetricProperty"></a>

								If a property, P, is tagged as

								symmetric then for any x and y:

								</p>

								<pre>

								P(x,y) iff P(y,x)

								</pre>

								<p>

								The property <tt>adjacentRegion</tt> is symmetric, while <tt>locatedIn</tt> is not.

								(To be more precise, <tt>locatedIn</tt> is not intended to be

								symmetric.  Nothing in the wine ontology at present prevents it from being symmetric.)


								</p>

								<pre>

								&lt;owl:ObjectProperty rdf:ID="adjacentRegion"&gt;

								  &lt;rdf:type rdf:resource="&amp;owl;SymmetricProperty" /&gt;

								  &lt;rdfs:domain rdf:resource="#Region" /&gt;

								  &lt;rdfs:range rdf:resource="#Region" /&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;Region rdf:ID="MendocinoRegion"&gt;

								  &lt;locatedIn rdf:resource="#CaliforniaRegion" /&gt;

								  &lt;adjacentRegion rdf:resource="#SonomaRegion" /&gt;

								&lt;/Region&gt;

								</pre>

								<p>

								The <tt>MendocinoRegion</tt> is adjacent to the <tt>SonomaRegion</tt>

								and vice-versa.  The <tt>MendocinoRegion</tt> is located in the

								<tt>CaliforniaRegion</tt> but not vice versa.

								</p>

								</dd>


								<dt><a name="FunctionalProperty">FunctionalProperty</a></dt>


								<dd>

								<p>

								<a id="owl_FunctionalProperty" name="owl_FunctionalProperty"></a>

								If a property, P, is tagged as functional then for all x, y, and z:

								</p>

								<pre>

								P(x,y) and P(x,z) implies y = z

								</pre>

								<p>

								In our wine ontology, <tt>hasVintageYear</tt>

								is functional.  A wine has a unique vintage year.

								That is, a given individual <tt>Vintage</tt> can only be associated with a

								single year using the <tt>hasVintageYear</tt> property.

								It is not a requirement of a <tt>owl:FunctionalProperty</tt>

								that all elements of the domain have values. See the discussion of

								<a href="#simpleCardinality"><tt>Vintage</tt> cardinality</a>.

								</p>

								<pre>

								&lt;owl:Class rdf:ID="VintageYear" /&gt;


								&lt;owl:ObjectProperty rdf:ID="hasVintageYear"&gt;

								  &lt;rdf:type rdf:resource="&amp;owl;FunctionalProperty" /&gt;

								  &lt;rdfs:domain rdf:resource="#Vintage" /&gt;

								  &lt;rdfs:range  rdf:resource="#VintageYear" /&gt;

								&lt;/owl:ObjectProperty&gt;

								</pre>

								</dd>


								<dt>inverseOf</dt>


								<dd>

								<p><a id="owl_inverseOf" name="owl_inverseOf"></a>

								If a property, P1, is tagged as the <tt>owl:inverseOf</tt> P2, then for

								all x, y, and z:

								</p>


								<pre>

								P1(x,y) iff P2(y,x)

								</pre>


								<p>

								Note that the syntax for <tt>owl:inverseOf</tt> takes a property name as an argument.

								<tt>A iff B</tt> means <tt>(A implies B) and (B implies A)</tt>.

								</p>


								<pre>

								&lt;owl:ObjectProperty rdf:ID="hasMaker"&gt;

								  &lt;rdf:type rdf:resource="&amp;owl;FunctionalProperty" /&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="producesWine"&gt;

								  &lt;owl:inverseOf rdf:resource="#hasMaker" /&gt;

								&lt;/owl:ObjectProperty&gt;

								</pre>


								<p>

								<tt>Wine</tt>s have makers, which in the definition of <tt>Wine</tt>

								are restricted to <tt>Winery</tt>s.  Then each

								<tt>Winery</tt> produces the set of wines that identify it as maker.

								</p>


								</dd>


								<dt>InverseFunctionalProperty</dt>


								<dd>

								<p>

								<a id="owl_InverseFunctionalProperty" name="owl_InverseFunctionalProperty"></a>

								If a property, P, is tagged as InverseFunctional then for all x and y:

								</p>


								<pre>

								P(y,x) and P(z,x) implies y = z

								</pre>


								<p>

								Notice that <tt>producesWine</tt> in the preceding section is inverse

								functional.  The reason is that the inverse of a functional property

								must be inverse functional.  We could have defined <tt>hasMaker</tt>

								and <tt>producesWine</tt> as follows and achieved the identical

								effect as the preceding example.

								</p>


								<pre>

								&lt;owl:ObjectProperty rdf:ID="hasMaker" /&gt;


								&lt;owl:ObjectProperty rdf:ID="producesWine"&gt;

								  &lt;rdf:type rdf:resource="&amp;owl;InverseFunctionalProperty" /&gt;

								  &lt;owl:inverseOf rdf:resource="#hasMaker" /&gt;

								&lt;/owl:ObjectProperty&gt;                                    <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>


								<p>

								Think of the elements of the range in an inverse functional property

								as defining a unique key in the database sense.

								<tt>owl:InverseFunctional</tt> implies that the elements of the range

								provide a unique identifier for each element of the domain.

								</p>

								<p>

								<a name="rdfs_Literal"/>

								In OWL Full, we can tag a <tt>DatatypeProperty</tt> as

								inverseFunctional.  This permits us to identify a string as

								a unique key.  In OWL DL literals are disjoint from owl:Thing, which

								is why OWL DL does not permit <tt>InverseFunctional</tt> to be applied to

								<tt>DatatypeProperty</tt>.

								</p>


								</dd>


								</dl>


								<h2>

								<a name="PropertyRestrictions" id="PropertyRestrictions"></a>

								<a name="restrictions" id="restrictions"></a>

								3.4. Property Restrictions</h2>


								<p>

								<a id="owl_Restriction" name="owl_Restriction"></a>

								<a id="owl_onProperty" name="owl_onProperty"></a>

								In addition to designating property characteristics, it is possible to

								further constrain the range of a property in specific contexts in a

								variety of ways.

								We do this with <i>property restrictions</i>.  The various

								forms described below can only be used within the context of an <tt>owl:Restriction</tt>.

								The <tt>owl:onProperty</tt> element indicates the restricted property.

								</p>

								<h3>

								<a name="allValuesFrom" id="allValuesFrom"></a>

								<a name="someValuesFrom" id="someValuesFrom"></a>

								<a id="owl_allValuesFrom" name="owl_allValuesFrom"></a>

								<a id="term_restriction_class" name="term_restriction_class"></a>

								3.4.1. allValuesFrom, someValuesFrom</h3>


								<p>

								We have already seen one way to restrict the types of the elements that

								make up a property.  The mechanisms to

								date have been <em>global</em> in that they apply to all

								instances of the property.  These next two, <tt>allValuesFrom</tt> and

								<tt>someValuesFrom</tt>, are <em>local</em> to their containing class definition.

								</p>

								<p>

								<!-- The <tt>owl:allValuesFrom</tt> restriction means that every instance of

								the class must have an instance of the specified property with

								values that are all instances of the specified restriction class. -->


								The <tt>owl:allValuesFrom</tt> restriction requires that for every instance of

								the class that has instances of the specified property, the

								values of the property are all members of the class indicated by the

								<tt>owl:allValuesFrom</tt> clause.

								</p>

								<pre>

								&lt;owl:Class rdf:ID="Wine"&gt;

								  &lt;rdfs:subClassOf rdf:resource="&amp;food;PotableLiquid" /&gt;

								  ...

								  &lt;rdfs:subClassOf&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#hasMaker" /&gt;

								      &lt;owl:allValuesFrom rdf:resource="#Winery" /&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/rdfs:subClassOf&gt;

								  ...

								&lt;/owl:Class&gt;

								</pre>


								<p>

								The maker of a <tt>Wine</tt> must be a <tt>Winery</tt>.

								The <tt>allValuesFrom</tt> restriction is on the <tt>hasMaker</tt> property of

								this <tt>Wine</tt> class <em>only</em>.  Makers of <tt>Cheese</tt> are

								not constrained by this local restriction.

								</p>


								<p>

								<a id="owl_someValuesFrom" name="owl_someValuesFrom"></a>

								<tt>owl:someValuesFrom</tt> is similar.   If we

								replaced <tt>owl:allValuesFrom</tt> with <tt>owl:someValuesFrom</tt>

								in the example above, it would mean that at least <em>one</em> of the

								<tt>hasMaker</tt> properties of a <tt>Wine</tt> must point to an

								individual that is a <tt>Winery</tt>.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Wine"&gt;

								  &lt;rdfs:subClassOf rdf:resource="&amp;food;PotableLiquid" /&gt;

								  &lt;rdfs:subClassOf&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#hasMaker" /&gt;

								      &lt;owl:someValuesFrom rdf:resource="#Winery" /&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/rdfs:subClassOf&gt;

								  ...

								&lt;/owl:Class&gt;                                            <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>


								<p>

								The difference between the two formulations is the difference between

								a universal and existential quantification.

								</p>


								<table class="propositions">

								<tr><th>Relation</th><th>Implications</th></tr>

								<tr><td>allValuesFrom</td><td>For all wines, if they have

								makers, all the makers are wineries.</td></tr>

								<tr><td>someValuesFrom&nbsp;&nbsp;</td><td>For all wines, they have at least one maker that is a winery.</td></tr>

								</table>


								<p>

								The first does not require a wine to have a maker.  If it does have one or more, they

								must all be wineries.  The second requires that there be at least one maker

								that is a winery, but there may be makers that are not wineries.

								</p>


								<h3><a name="simpleCardinality" id="simpleCardinality">3.4.2. Cardinality</a></h3>


								<p>

								<a id="owl_cardinality" name="owl_cardinality"></a>

								<a id="term_cardinality" name="term_cardinality"></a>

								We have already seen examples of cardinality constraints.  To date,

								they have been assertions about minimum cardinality.  Even more

								straight-forward is <tt>owl:cardinality</tt>, which permits the

								specification of <em>exactly</em> the number of elements in a relation.

								For example, we specify <tt>Vintage</tt> to be a class  with

								exactly one <tt>VintageYear</tt>.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Vintage"&gt;

								  &lt;rdfs:subClassOf&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#hasVintageYear"/&gt;

								      &lt;owl:cardinality rdf:datatype="&amp;xsd;nonNegativeInteger"&gt;1&lt;/owl:cardinality&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/rdfs:subClassOf&gt;

								&lt;/owl:Class&gt;

								</pre>


								<p>

								We specified <tt>hasVintageYear</tt> to be a functional property, which

								is the same as saying that every Vintage has at most one VintageYear.

								This application of that property to <tt>Vintage</tt> using the

								cardinality restriction asserts

								something stronger, that <em>every</em> <tt>Vintage</tt> has

								<em>exactly</em> one <tt>VintageYear</tt>.

								</p>

								<!--

								<p>

								As another example, the following asserts that a <tt>Meal</tt> has at least

								two <tt>course</tt>s.

								</p>

								<pre>

								&lt;owl:Class rdf:ID="Meal"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#ConsumableThing" /&gt;

								  &lt;rdfs:subClassOf&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#course" /&gt;

								      &lt;owl:minCardinality rdf:datatype="&amp;xsd;nonNegativeInteger"&gt;1&lt;/owl:minCardinality&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/rdfs:subClassOf&gt;

								  ...

								&lt;/owl:Class&gt;

								</pre>

								-->

								<p>

								<a id="owl_minCardinality" name="owl_minCardinality"></a>

								<a id="owl_maxCardinality" name="owl_maxCardinality"></a>

								Cardinality expressions with values limited to 0 or 1 are part of OWL Lite.

								This permits the user to indicate 'at least one', 'no more than one',

								and 'exactly one'.

								Positive integer values other than 0 and 1 are permitted in OWL DL.

								<tt>owl:maxCardinality</tt> can be used to specify an <em>upper</em> bound.

								<tt>owl:minCardinality</tt> can be used to specify a <em>lower</em> bound.

								In combination, the two can be used to limit the property's cardinality to

								a numeric interval.

								</p>


								<!--

								<p>

								MinCardinality defaults to 0.

								There is no default value for cardinality or maxCardinality.

								</p>

								-->


								<h3><a id="hasValue" name="hasValue">3.4.3. hasValue</a> <a href="#OWL_DL_tag">[OWL DL]</a></h3>


								<p>

								<a id="owl_hasValue" name="owl_hasValue"></a>

								<tt>hasValue</tt> allows us to specify classes based on the

								existence of <em>particular</em> property values. Hence,

								an individual will be a member of such a class whenever at least <em>one</em>

								of its property values is equal to the hasValue resource.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Burgundy"&gt;

								  ...

								  &lt;rdfs:subClassOf&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#hasSugar" /&gt;

								      &lt;owl:hasValue rdf:resource="#Dry" /&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/rdfs:subClassOf&gt;

								&lt;/owl:Class&gt;

								</pre>


								<p>

								Here we declare that all <tt>Burgundy</tt> wines are dry.  That is, their

								<tt>hasSugar</tt> property must have at least one value that is equal

								to <tt>Dry</tt>.

								</p>


								<p>

								As for <tt>allValuesFrom</tt> and

								<tt>someValuesFrom</tt>, this is a local restriction.  It holds for

								<tt>hasSugar</tt> as applied to <tt>Burgundy</tt>.

								</p>


								<h1><a name="OntologyMapping">4. Ontology Mapping </a></h1>


								<p>

								In order for ontologies to have the maximum impact, they need to be

								widely shared.  In order to minimize the intellectual effort involved

								in developing an ontology they need to be re-used.  In the best of all

								possible worlds they need to be composed.  For example, you might adopt

								a date ontology from one source and a physical location ontology from

								another and then extend the notion of location to include the time

								period during which it holds.

								</p>

								<p>

								It is important to realize that much of the effort of developing an

								ontology is devoted to hooking together classes and properties in

								ways that maximize implications.  We want simple assertions about

								class membership to

								have broad and useful implications.  This is the hardest part of

								ontology development.  If you can find an existing ontology that has

								already undergone extensive use and refinement, it makes sense to

								adopt it.

								</p>

								<p>

								It will be challenging to merge a collection of ontologies.  Tool

								support will almost certainly be required to maintain consistency.

								</p>


								<h2><a name="equivalentClass1" id="equivalentClass1">

								4.1. Equivalence between Classes and Properties<br />

								<tt>equivalentClass</tt>, <tt>equivalentProperty</tt></a></h2>


								<p>To tie together a set of component ontologies as part of a

								third it is frequently useful to be able to indicate that a particular

								class or property in one ontology is equivalent to a class or property

								in a second

								ontology.  This capability must be used with care.

								If the combined ontologies are contradictory (all A's

								are B's vs. all A's are not B's) there will be no extension (no

								individuals and relations) that satisfies the resulting combination.

								</p>


								<p>

								<a id="owl_equivalentClass" name="owl_equivalentClass"></a>

								<a id="owl_sameClassAs" name="owl_sameClassAs"></a>

								In the food ontology we want to link wine features in the descriptions

								of dining courses back to the wine ontology.  One way to do this is by

								defining a class in the food ontology and then

								declaring it equivalent to an existing wine class in the wine ontology.

								</p>

								<pre>

								&lt;owl:Class rdf:ID="Wine"&gt;

								  &lt;owl:equivalentClass rdf:resource="&amp;vin;Wine"/&gt;

								&lt;/owl:Class&gt;

								</pre>

								<p>

								The property <tt>owl:equivalentClass</tt> is used to indicate that two classes have

								precisely the same instances.  Note that in OWL DL, classes simply denote sets

								of individuals, and are not individuals themselves.  In OWL Full, however,

								we can use <a href="#owl_sameAs"><tt>owl:sameAs</tt></a>

								between two classes to indicate that

								they are identical in every way.

								</p>


								<p>

								Of course the example above is somewhat contrived, since we can always

								use <tt>&amp;vin;Wine</tt> anywhere we would use <tt>#Wine</tt> and get

								the same effect without redefinition.  A more likely use would be in a

								case were we depend on two independently developed ontologies, and

								note that they use the URI's <tt>O1:foo</tt> and <tt>O2:bar</tt> to

								reference the same class.  <tt>owl:equivalentClass</tt> could be used to

								collapse these together so that the entailments from the two

								ontologies are combined.

								</p>


								<p>

								We have already seen that class expressions can be the targets

								of <tt>rdfs:subClassOf</tt> constructors.  They can also be the target of

								<tt>owl:equivalentClass</tt>.  Again, this avoids the need to

								contrive names for every class expression and provides a powerful

								definitional capability based on satisfaction of a property.

								</p>

								<pre>

								&lt;owl:Class rdf:ID="TexasThings"&gt;

								  &lt;owl:equivalentClass&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#locatedIn" /&gt;

								      &lt;owl:allValuesFrom rdf:resource="#TexasRegion" /&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/owl:equivalentClass&gt;

								&lt;/owl:Class&gt;                                               <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>

								<p>


								<tt>TexasThings</tt> are <em>exactly</em> those things located in the

								Texas region.  The difference between using <tt>owl:equivalentClass</tt> here

								and using <tt>rdfs:subClassOf</tt> is the difference between a necessary

								condition and a necessary and sufficient condition.  With

								<tt>subClassOf</tt>, things that are located in Texas are not

								necessarily <tt>TexasThings</tt>.  But, using <tt>owl:equivalentClass</tt>, if

								something is located in Texas, then it must be in the class of

								<tt>TexasThings</tt>.

								</p>

								<table class="propositions">

								<tr><th>Relation</th><th>Implications</th></tr>

								<tr><td>subClassOf</td><td>TexasThings(x) implies locatedIn(x,y) and TexasRegion(y)</td></tr>

								<tr><td>equivalentClass&nbsp;&nbsp;</td><td>TexasThings(x) implies

								locatedIn(x,y) and TexasRegion(y)<br />locatedIn(x,y) and

								TexasRegion(y) implies TexasThings(x)</td></tr>

								</table>


								<p>

								<a id="owl_equivalentProperty" name="owl_equivalentProperty"></a>

								<a id="owl_samePropertyAs" name="owl_samePropertyAs"></a>

								To tie together properties in a similar fashion, we use

								<tt>owl:equivalentProperty</tt>.

								</p>


								<h2>

								<a id="owl_sameAs" name="owl_sameAs"></a>

								<a id="sameAs" name="sameAs">

								4.2. Identity between Individuals<br />

								<tt>sameAs</tt></a></h2>


								<p>This mechanism is similar to that for classes, but declares two

								individuals to be identical.  An example would be:

								</p>

								<pre>

								&lt;Wine rdf:ID="MikesFavoriteWine"&gt;

								  &lt;owl:sameAs rdf:resource="#StGenevieveTexasWhite" /&gt;

								&lt;/Wine&gt;                                                 <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>

								<p>

								This example does not have great utility.  About all we learn from this is

								that Mike likes an inexpensive local wine.  A more typical use of

								<tt>sameAs</tt> would be to equate individuals defined in

								different documents to one another, as part of unifying two ontologies.

								</p>


								<p>

								This brings up an important point.  OWL does not have a

								<a id="term_uniqueName" name="term_uniqueName"></a><em>unique

								name</em> assumption.  Just because two names are different does not

								mean they refer to different individuals.

								</p>


								<p>

								In the example above, we <em>asserted</em> identity between two distinct

								names.  But it is just as possible for this sort of identity to be

								inferred.

								Remember the implications that can be derived from a functional

								property.  Given that <tt>hasMaker</tt> is functional, the following

								is not necessarily a conflict.

								</p>

								<pre>

								&lt;owl:Thing rdf:about="#BancroftChardonnay"&gt;

								  &lt;hasMaker rdf:resource="#Bancroft" /&gt;

								  &lt;hasMaker rdf:resource="#Beringer" /&gt;

								&lt;/owl:Thing&gt;                                            <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>

								<p>

								Unless this conflicts with other information in our ontology, it simply means

								that <tt>Bancroft</tt> = <tt>Beringer</tt>.

								</p>


								<p>

								Note that using <tt>sameAs</tt> to equate two classes

								is <b>not</b> the same as equating them with <tt>equivalentClass</tt>; instead, it causes the

								the classes to be interpreted as individuals, and is therefore sufficient

								to categorize an ontology as OWL Full.

								In OWL Full <tt>sameAs</tt> may be used to equate

								anything: a class and an individual, a property and a class, etc., and causes both

								arguments to be intepreted as individuals.

								</p>


								<h2><a name="differentFrom">4.3. Different Individuals<br />

								<tt>differentFrom</tt>, <tt>AllDifferent</tt></a></h2>


								<p>

								<a id="owl_differentFrom" name="owl_differentFrom"></a>

								This mechanism provides the opposite effect from sameAs.

								</p>

								<pre>

								&lt;WineSugar rdf:ID="Dry" /&gt;


								&lt;WineSugar rdf:ID="Sweet"&gt;

								  &lt;owl:differentFrom rdf:resource="#Dry"/&gt;

								&lt;/WineSugar&gt;


								&lt;WineSugar rdf:ID="OffDry"&gt;

								  &lt;owl:differentFrom rdf:resource="#Dry"/&gt;

								  &lt;owl:differentFrom rdf:resource="#Sweet"/&gt;

								&lt;/WineSugar&gt;

								</pre>


								<p>

								This is one way to assert that these three values are mutually distinct.

								There will be cases where it is important to ensure such distinct

								identities.  Without these assertions we could describe a wine that was

								both <tt>Dry</tt> and <tt>Sweet</tt>.  We have

								stated that the <tt>hasSugar</tt> property applied to a wine has no more than

								one value.  If we erred, and asserted that a wine was both <tt>Dry</tt> and

								<tt>Sweet</tt>, without the <tt>differentFrom</tt> elements above,

								this would imply that <tt>Dry</tt> and <tt>Sweet</tt> are identical.

								With the elements above, we would instead get a contradiction.

								</p>


								<p>

								<a id="owl_AllDifferent" name="owl_AllDifferent"></a>

								<a id="owl_distinctMembers" name="owl_distinctMembers"></a>

								A more convenient mechanism exists to define a set of mutually

								distinct individuals.  The following asserts that <tt>Red</tt>,

								<tt>White</tt>, and <tt>Rose</tt> are pairwise distinct.

								</p>

								<pre>

								&lt;owl:AllDifferent&gt;

								  &lt;owl:distinctMembers rdf:parseType="Collection"&gt;

								    &lt;vin:WineColor rdf:about="#Red" /&gt;

								    &lt;vin:WineColor rdf:about="#White" /&gt;

								    &lt;vin:WineColor rdf:about="#Rose" /&gt;

								  &lt;/owl:distinctMembers&gt;

								&lt;/owl:AllDifferent&gt;

								</pre>

								<p>Note that <tt>owl:distinctMembers</tt> can only be used

								in combination with <tt>owl:AllDifferent</tt>

								</p>

								<p>

								In the wine ontology we provide an <tt>owl:AllDifferent</tt> assertion

								for all of the <tt>WineDescriptor</tt>s.  We also state that

								the <tt>Winery</tt>s are all different.  If we wanted to add a new

								winery in some other ontology and assert that it was disjoint from all

								of those that have already been defined, we would need to cut and

								paste the original <tt>owl:AllDifferent</tt> assertion and add the new

								maker to the list.  There is not a simpler way to extend an

								<tt>owl:AllDifferent</tt> collection in OWL DL.  In OWL Full, using

								RDF triples and the rdf:List constructs, other approaches are possible.

								</p>


								<hr />


								<h1><a name="ComplexClasses">5. Complex Classes</a>

								 <a href="#OWL_DL_tag">[OWL DL]</a></h1>


								<p>

								OWL provides additional constructors with which to form classes. These

								constructors can be used to create so-called <em>class

								expressions</em>. OWL supports the basic set operations, namely

								union, intersection and complement.  These are named

								<tt>owl:unionOf</tt>, <tt>owl:intersectionOf</tt>, and <tt>owl:complementOf</tt>,

								respectively. Additionally, classes can be

								<a id="term_enumerated" name="term_enumerated"></a><em>enumerated</em>.

								Class extensions can be stated explicitly by means of the

								<tt>oneOf</tt> constructor.

								And it is possible to assert that class extensions must be disjoint.

								</p>


								<p>

								Note that Class expressions can be nested without requiring the creation

								of names for every intermediate class.

								This allows the use of set operations to build up complex classes

								from anonymous classes or classes with value restrictions.

								</p>


								<h2><a name="SetOperators" id="SetOperators">5.1. Set Operators</a><br />

								<tt>intersectionOf, unionOf, complementOf</tt>

								</h2>


								<p>

								Remember that OWL class extensions are sets consisting of the individuals

								that are members of the class. OWL provides the means to

								manipulate class extensions using basic set operators.

								</p>


								<h3><a id="owl_intersectionOf" name="owl_intersectionOf">5.1.1. Intersection</a>

								 <a href="#OWL_DL_tag">[some uses OWL DL]</a></h3>


								<p>


								The following examples demonstrate the use of the

								<a id="term_intersection" name="term_intersection"></a><em>intersectionOf</em> construct.

								</p>

								<pre>

								&lt;owl:Class rdf:ID="WhiteWine"&gt;

								  &lt;owl:intersectionOf rdf:parseType="Collection"&gt;

								    &lt;owl:Class rdf:about="#Wine" /&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#hasColor" /&gt;

								      &lt;owl:hasValue rdf:resource="#White" /&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/owl:intersectionOf&gt;

								&lt;/owl:Class&gt;

								</pre>

								<p>

								Classes constructed using the set operations are more like

								definitions than anything we have seen to date.

								The members of the class are completely specified by

								the set operation.

								The construction above states that <tt>WhiteWine</tt> is <em>exactly</em> the

								intersection of the class <tt>Wine</tt> and the set of things that are

								white in color.  This means that if something is white and a wine,

								then it is an instance of <tt>WhiteWine</tt>.  Without such a definition

								we can know that white wines are wines and white, but not vice-versa.

								This is an important tool for categorizing individuals.

								(Note that 'rdf:parseType="Collection"' is a required syntactic element.)


								</p>

								<pre>

								&lt;owl:Class rdf:about="#Burgundy"&gt;

								  &lt;owl:intersectionOf rdf:parseType="Collection"&gt;

								    &lt;owl:Class rdf:about="#Wine" /&gt;

								    &lt;owl:Restriction&gt;

								      &lt;owl:onProperty rdf:resource="#locatedIn" /&gt;

								      &lt;owl:hasValue rdf:resource="#BourgogneRegion" /&gt;

								    &lt;/owl:Restriction&gt;

								  &lt;/owl:intersectionOf&gt;

								&lt;/owl:Class&gt;

								</pre>


								<p>

								Here we define <tt>Burgundy</tt> to include exactly those wines that have

								at least one <tt>locatedIn</tt> relation to the Bourgogne Region.

								We could have declared a new class

								<tt>ThingsFromBourgogneRegion</tt> and used it as a class in the

								<tt>owl:intersectionOf</tt> construct.  Since we do not have any other

								use for <tt>ThingsFromBourgogneRegion</tt>, the declaration above is

								shorter, clearer and doesn't require the creation of a contrived name.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="WhiteBurgundy"&gt;

								  &lt;owl:intersectionOf rdf:parseType="Collection"&gt;

								    &lt;owl:Class rdf:about="#Burgundy" /&gt;

								    &lt;owl:Class rdf:about="#WhiteWine" /&gt;

								  &lt;/owl:intersectionOf&gt;

								&lt;/owl:Class&gt;

								</pre>

								<p>

								Finally, the class <tt>WhiteBurgundy</tt> is exactly the intersection of

								white wines and Burgundies.  Burgundies in turn are grown in the

								French region of Bourgogne and are dry wines.  Accordingly all

								individual wines that meet these criteria are part of the class

								extension of <tt>WhiteBurgundy</tt>.

								</p>


								<h3><a id="owl_unionOf" name="owl_unionOf">5.1.2. Union</a> <a href="#OWL_DL_tag">[OWL DL]</a></h3>


								<p>


								The following example demonstrates the use of the

								<a id="term_union" name="term_union"></a><em>unionOf</em> construct. It is used exactly like the

								<em>intersectionOf</em> construct:

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Fruit"&gt;

								  &lt;owl:unionOf rdf:parseType="Collection"&gt;

								    &lt;owl:Class rdf:about="#SweetFruit" /&gt;

								    &lt;owl:Class rdf:about="#NonSweetFruit" /&gt;

								  &lt;/owl:unionOf&gt;

								&lt;/owl:Class&gt;

								</pre>


								<p>

								The class <tt>Fruit</tt> includes <em>both</em>

								the extension of <tt>SweetFruit</tt> and the extension of

								<tt>NonSweetFruit</tt>.

								</p>


								<p>

								Note how completely different this union type construct is from the following.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Fruit"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#SweetFruit" /&gt;

								  &lt;rdfs:subClassOf rdf:resource="#NonSweetFruit" /&gt;

								&lt;/owl:Class&gt;                                            <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>


								<p>

								This says that the instances of <tt>Fruit</tt> are a subset of the

								<em>intersection</em> of sweet and non-sweet fruit, which we would

								expect to be the empty set.

								</p>


								<h3><a id="owl_complementOf" name="owl_complementOf">

								5.1.3. Complement</a> <a href="#OWL_DL_tag">[OWL DL]</a></h3>


								<p>

								The <a id="term_complement" name="term_complement"></a><em>complementOf</em> construct selects all individuals from

								the domain of discourse that do not belong to a certain

								class. Usually this refers to a very large set of individuals:

								</p>

								<pre>

								  &lt;owl:Class rdf:ID="ConsumableThing" /&gt;


								  &lt;owl:Class rdf:ID="NonConsumableThing"&gt;

								    &lt;owl:complementOf rdf:resource="#ConsumableThing" /&gt;

								  &lt;/owl:Class&gt;

								</pre>


								<p>

								The class of <tt>NonConsumableThing</tt> includes as its members

								all individuals that do not belong to the extension

								of <tt>ConsumableThing</tt>.  This set includes all

								<tt>Wine</tt>s, <tt>Region</tt>s, etc.  It is literally the set

								difference between <tt>owl:Thing</tt> and  <tt>ConsumableThing</tt>.

								Therefore, a typical usage pattern for

								<em>complementOf</em> is in combination with other set

								operators:

								</p>

								<pre>

								&lt;owl:Class rdf:ID="NonFrenchWine"&gt;

								  &lt;owl:intersectionOf rdf:parseType="Collection"&gt;

								    &lt;owl:Class rdf:about="#Wine"/&gt;

								    &lt;owl:Class&gt;

								      &lt;owl:complementOf&gt;

								        &lt;owl:Restriction&gt;

								          &lt;owl:onProperty rdf:resource="#locatedIn" /&gt;

								          &lt;owl:hasValue rdf:resource="#FrenchRegion" /&gt;

								        &lt;/owl:Restriction&gt;

								      &lt;/owl:complementOf&gt;

								    &lt;/owl:Class&gt;

								  &lt;/owl:intersectionOf&gt;

								&lt;/owl:Class&gt;                                            <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>


								<p>

								<!-- MORE ????

								From Guide comments:


								The example at the end is very complex because it uses the

								TransitiveProperty feature of locatedIn for warranting that whatever

								is declared to be in, say, Bourgogne, will also be locatedIn

								FrenchRegion. I would add a couple of sentences to explain it.

								-->


								This defines the class <tt>NonFrenchWine</tt> to be the

								intersection of <tt>Wine</tt> with the set of all

								things <em>not</em> located in <tt>France</tt>.

								</p>


								<h2><a name="EnumeratedClasses">5.2. Enumerated Classes</a><br />

								<tt>oneOf</tt> <a href="#OWL_DL_tag">[OWL DL]</a></h2>


								<p>

								OWL provides the means to specify a class via a direct enumeration of its

								members. This is done using the <em>oneOf</em> constructor. Notably,

								this definition completely specifies the class extension, so that no other

								individuals can be declared to belong to the class.

								</p>


								<p>

								<a id="owl_oneOf" name="owl_oneOf"></a>

								The following defines a class <tt>WineColor</tt> whose

								members are the individuals <tt>White</tt>, <tt>Rose</tt>, and

								<tt>Red</tt>.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="WineColor"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#WineDescriptor"/&gt;

								  &lt;owl:oneOf rdf:parseType="Collection"&gt;

								    &lt;owl:Thing rdf:about="#White"/&gt;

								    &lt;owl:Thing rdf:about="#Rose"/&gt;

								    &lt;owl:Thing rdf:about="#Red"/&gt;

								  &lt;/owl:oneOf&gt;

								&lt;/owl:Class&gt;

								</pre>


								<p>

								The first thing to understand here is that no other individuals can be

								a valid <tt>WineColor</tt> since the class has been defined by

								enumeration.

								</p>


								<p>

								Each element of the <tt>oneOf</tt> construct must be a validly declared

								individual. An individual has to belong to some class. In the above

								example, each individual was referenced by name.  We used

								<tt>owl:Thing</tt> as a simple clich&eacute; to introduce the reference.

								Alternatively, we could have referenced the elements of the set

								according to their specific type, <tt>WineColor</tt>, by:

								</p>


								<pre>

								&lt;owl:Class rdf:ID="WineColor"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#WineDescriptor"/&gt;

								  &lt;owl:oneOf rdf:parseType="Collection"&gt;

								    &lt;WineColor rdf:about="#White" /&gt;

								    &lt;WineColor rdf:about="#Rose" /&gt;

								    &lt;WineColor rdf:about="#Red" /&gt;

								  &lt;/owl:oneOf&gt;

								&lt;/owl:Class&gt;

								</pre>


								<p>

								Other, more complex descriptions of individuals are also valid

								elements of the <em>oneOf</em> construct, for example:

								</p>


								<pre>

								&lt;WineColor rdf:about="#White"&gt;

								  &lt;rdfs:label&gt;White&lt;/rdfs:label&gt;

								&lt;/WineColor&gt;                                            <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>


								<h2><a id="DisjointClasses" name="DisjointClasses">5.3. Disjoint Classes</a> <br />

								<tt>disjointWith</tt> <a href="#OWL_DL_tag">[OWL DL]</a></h2>


								<p>

								<a id="owl_disjointWith" name="owl_disjointWith"></a>

								The disjointness of a set of classes can be expressed using the

								<tt>owl:disjointWith</tt> constructor. It guarantees that an

								individual that is a member of one class cannot simultaneously be an

								instance of a specified other class.

								</p>


								<pre>

								&lt;owl:Class rdf:ID="Pasta"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#EdibleThing"/&gt;

								  &lt;owl:disjointWith rdf:resource="#Meat"/&gt;

								  &lt;owl:disjointWith rdf:resource="#Fowl"/&gt;

								  &lt;owl:disjointWith rdf:resource="#Seafood"/&gt;

								  &lt;owl:disjointWith rdf:resource="#Dessert"/&gt;

								  &lt;owl:disjointWith rdf:resource="#Fruit"/&gt;

								&lt;/owl:Class&gt;

								</pre>


								<p>

								The <tt>Pasta</tt> example demonstrates multiple disjoint classes.

								Note that this only asserts that <tt>Pasta</tt> is disjoint from all

								of these other classes.  It does not assert, for example, that

								<tt>Meat</tt> and <tt>Fruit</tt> are disjoint.  In order to assert

								that a set of classes is mutually disjoint, there must be an

								<tt>owl:disjointWith</tt> assertion for every pair.

								</p>


								<p>

								A common requirement is to define

								a class as the union of a set of mutually disjoint subclasses.

								</p>

								<pre>

								&lt;owl:Class rdf:ID="SweetFruit"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#EdibleThing" /&gt;

								&lt;/owl:Class&gt;


								&lt;owl:Class rdf:ID="NonSweetFruit"&gt;

								  &lt;rdfs:subClassOf rdf:resource="#EdibleThing" /&gt;

								  &lt;owl:disjointWith rdf:resource="#SweetFruit" /&gt;

								&lt;/owl:Class&gt;


								&lt;owl:Class rdf:ID="Fruit"&gt;

								  &lt;owl:unionOf rdf:parseType="Collection"&gt;

								    &lt;owl:Class rdf:about="#SweetFruit" /&gt;

								    &lt;owl:Class rdf:about="#NonSweetFruit" /&gt;

								  &lt;/owl:unionOf&gt;

								&lt;/owl:Class&gt;

								</pre>


								<p>

								Here we define <tt>Fruit</tt> to be exactly the union of

								<tt>SweetFruit</tt> and <tt>NonSweetFruit</tt>.  And we know that

								these subclasses exactly partition <tt>Fruit</tt> into two distinct subclasses

								because they are disjoint.

								As the number of mutually disjoint classes

								grows, the number of disjointness assertions grows proportionally to

								n<sup>2</sup>.  However, in the use cases we have seen, n is typically

								small.

								</p>


								<hr />


								<h1><a name="OntologyVersioning" id="OntologyVersioning"></a>

								<a name="term_version" id="term_version"></a>

								6. Ontology Versioning</h1>


								<p>

								<a id="owl_priorVersion" name="owl_priorVersion"></a>

								Ontologies are like software, they will be maintained and thus will change

								over time.

								Within an <tt>owl:Ontology</tt> element

								(discussed <a href="#OntologyHeaders">above</a>), it is possible to link to a previous

								version of the ontology being defined.  The <tt>owl:priorVersion</tt> property

								is intended to provide this link, and can be used to track the

								version history of an ontology.

								</p>

								<pre>

								&lt;owl:Ontology rdf:about=""&gt;

								  ...

								  &lt;owl:priorVersion rdf:resource="http://www.w3.org/TR/2003/WD-owl-guide-20030331/wine"/&gt;

								  ...

								&lt;/owl:Ontology&gt;

								</pre>

								<p>

								The indicated ontology is a previous version of the one being defined.

								</p>


								<p>

								<a id="owl_backwardCompatibleWith" name="owl_backwardCompatibleWith"></a>

								<a id="owl_incompatibleWith" name="owl_incompatibleWith"></a>

								Ontology versions may not be compatible with each other.  For example, a

								prior version of an ontology may contain statements that contradict the current

								version.    Within an <tt>owl:Ontology</tt> element,

								we use the tags <tt>owl:backwardCompatibleWith</tt>

								and <tt>owl:incompatibleWith</tt> to indicate compatibility or the

								lack thereof with previous ontology versions.

								If <tt>owl:backwardCompatibleWith</tt> is not declared, then

								compatibility should not be assumed.

								<a id="owl_versionInfo" name="owl_versionInfo"></a>

								In addition, <tt>owl:versionInfo</tt>

								provides a hook suitable for use by versioning systems.  As opposed to the previous three tags,

								the object of <tt>owl:versionInfo</tt> is a literal and the tag can be used

								to annotate classes and properties in addition to ontologies.

								</p>

								<p>

								<a id="owl_DeprecatedClass" name="owl_DeprecatedClass"></a>

								<a id="owl_DeprecatedProperty" name="owl_DeprecatedProperty"></a>

								For many purposes, doing version tracking at the granularity of

								an entire ontology is not enough.  Maintainers may wish to keep

								version information for classes, properties, and individuals - and

								even that may not be sufficient.  The incremental nature of class expressions

								in OWL implies that one ontology may add restrictions to a (named) class defined

								in another ontology, and

								these additional restrictions themselves may require version information.

								</p>

								<p>

								OWL Full provides the expressive power to make any sort of assertion about a class,

								i.e. that it is an instance of another class, or that it (and not its instances) has

								a property and a value for that property.  This framework can be used

								to build an ontology of classes and properties for tracking version information.

								The OWL namespace includes two pre-defined classes that can be used for this purpose:

								<tt>owl:DeprecatedClass</tt>

								and <tt>owl:DeprecatedProperty</tt>.

								They are intended to indicate that the class or property will likely be changing in an

								incompatible manner in a forthcoming release:

								</p>

								<pre>

								...

								  &lt;owl:DeprecatedClass rdf:ID="&amp;vin;JugWine" /&gt;

								  &lt;owl:DeprecatedProperty rdf:ID="&amp;vin;hasSeeds" /&gt;

								...                                                           <span class="red">&nbsp;&not;&nbsp;</span>

								</pre>

								<p>

								It is important to note that <tt>owl:DeprecatedClass</tt>

								and <tt>owl:DeprecatedProperty</tt>

								have no additional semantics and it is up to tool

								developers and OWL users to ensure they are used as intended.

								</p>


								<!--

								<li>They should provide a useful starting point for defining a more

								extensive ontology of versioning properties and classes.</li>


								<li>Using these classes in an ontology makes it an OWL Full ontology.

								However, users who need versioning and who wish their ontologies to

								remain in OWL DL or OWL Lite can do so by separating these versioning

								statements into another ontology that imports the one for which

								versioning information is needed.</li>

								</ul>

								-->


								<hr />


								<h1><a name="Usage" id="Usage">7. Usage Examples</a></h1>


								<p>

								Once an initial domain ontology is available, a

								large number of applications can be developed that exploit the

								ontology.  In this section, we describe some

								sample uses in the domain of wines.


								</p>


								<h2><a id="WinePortal" name="WinePortal">7.1. Wine Portal</a></h2>


								<p>

								A number of sites exist today that call themselves wine portals.

								Google for example, provides 152,000 matches for the query "wine

								portal".  One of the top matches, a site called

								<a href="http://www.Wine-Portal.com">"Wine-Portal.com"</a>,

								provides access to a number of sites.  Many sites

								claiming to be wine portals are mostly informational sites.  For

								example, wine-portal.com's first featured site, called 'cork cuisine'

								(<a href="http://www.corkcuisine.com">www.corkcuisine.com/</a>),

								provides information about matching

								wines and foods, wines as gifts, etc.  Another site billed as "the

								Internet Wine Portal" (<a href="http://www.cyberbacchus.com/">

								www.cyberbacchus.com/</a>) provides a nice

								organization of a substantial amount of wine information on

								numerous topics.

								</p>


								<p>

								Perusing any of the topic areas, one finds a collection of pages

								containing information and sometimes services related to the topic.

								For example, 'accessories and gifts' contains information about what to

								look for when buying particular wine items and also contains a

								significant number of online retailers.  Another top level area called

								'shopping' has a subarea called 'wine shopping' from which a user can find

								online (or 'street shopping') stores (categorized by country).

								These two sites are just two of the many examples

								today and are representative of the general notion of a wine portal providing

								a collection of information and services connected to a particular topic

								area.

								</p>

								<p>

								When looking at these sites in some detail, it is not clear how much

								they depend on ontologies today.  For example, viewing the source

								for the html does not reveal evidence of ontological usage.  However,

								it is clear that the sites could exploit ontologies had some wine ontologies

								been available.

								</p>

								<p>

								One simple use of ontologies in portal sites is for organization and

								browsing.  The listing of categories above could be generated from

								the top few levels of wine related classes.  Queries could exploit

								wine ontologies to <i>retrieve</i> wine relevant information.

								If one did a search for a term contained in the ontology, the query could

								be expanded with subclass information in order to find more relevant answers.


								Portals could be made to automatically update themselves with (candidate) information

								in topic areas.  With very powerful reasoning

								capabilities they could even identify likely wine sales sites and

								negotiate to include them as part of the portal.


								</p>


								<h2><a id="WineAgent" name="WineAgent">7.2. Wine Agent</a></h2>


								<p>

								We have started a <a href="http://www.ksl.stanford.edu/people/dlm/webont/wineAgent/">

								wine agent</a> for expository purposes. In our initial design,

								the wine agent's goal is to recommend wines to accompany meal courses.

								This application exploits the ontology used as the basis of this guide.

								This wine ontology is available in the DAML ontology library and is entitled

								<a href="http://www.daml.org/ontologies/76">wines.</a>

								</p>


								<p>A personalized wine agent can provide a number of services for a human.

								<br />The agent may be used to recommend wines given a set of constraints

								(such as a meal being served),  the agent may find information about

								a particular wine or a particular class of wines, it may look for appropriate

								accessories for a wine (such as a particular kind of glass suited for that

								wine varietal, etc.).

								</p>


								<p>Below, we describe an example in a simple prototype system that is being

								written as a student project.

								</p>


								<p>Consider the following scenario:<br /><br />

								Someone is planning a dinner party and at least one of the guests is

								wine knowledgeable.  The host would like to serve wine that is well

								matched to the course(s) on the menu.  The host would also like to

								appear knowledgeable about the wines served at the event.  The host

								would also like to have appropriate accessories at the dinner. The host

								may have decided to serve a special tomato based pasta sauce with fresh

								pasta as the main course.

								</p>


								<p>In order to serve wines appropriate to the meal, the host needs information

								concerning wine and food pairings.  In order to appear knowledgeable

								about wines, the host would benefit from having access to wine information

								relevant to the event.  In order to have appropriate wine accessories,

								the host would need to have information about what accessories are relevant

								to the situation (and are within the host's price range).

								</p>


								<p>

								With a background wine ontology, given a description of a meal, a wine

								agent can suggest the type of wine to serve with the meal.  The wine

								agent may suggest a zinfandel as the varietal of choice for the meal.

								Additionally, given a background ontology, the wine agent may suggest a

								particular zinfandel, possibly Marietta Zinfandel. Given the information

								that the wine should be a zinfandel, a wine agent may look for a place

								to acquire either a selection of zinfandels or it may look for a particular

								zinfandel wine, such as Marietta.  Given a background ontology containing

								appropriate sources for wine purchases (possibly filtered by the location

								of the host and the location of the wine seller), the wine agent could

								go to a site such as <a href="http://www.wine.com/">wine.com</a> and do

								a search for zinfandels returning a <a href="http://www.wine.com/search/ea_results.asp?ct=1577&amp;query=zinfandel">listing</a>

								of zinfandels for sale on that site.  The wine agent could attempt

								to find <a href="http://www.b-21.com/marietta/">Marietta</a> <a href="http://www.mariettacellars.com/welcome.html">Zinfandel</a>

								either from the winery itself or from other resellers.  It could,

								for example, find (by a search on Google or a structured search of selected

								Web sites) that winelibrary.com has a sale on Marietta Zinfandel 1999 vintage

								for a discounted price of $13.99.    The wine agent could

								use additional filtering information such as price ranges provided either

								by the consumer or as suggestions based on varietal.

								</p>


								<p>

								The wine agent may now attempt to provide information concerning

								zinfandel in general or Marietta Zinfandel in particular.  It could

								use a background ontology of wine sites to find information about

								particular wines.  For example, the winery <a href="http://www.mariettacellars.com/welcome.html">description</a> of

								their most recent Zinfandel may be of use.

								Additionally reviews from respected sources such as the <a

								href="http://www.winespectator.com/Wine/Home">Wine Spectator</a> may

								be of use.  If no review of Marietta Zinfandel is available on a

								favorite wine review site, it may be useful to look for related

								information such as reviews on zinfandels from the same region, in

								this case zinfandels from Sonoma County, California.

								</p>


								<p>

								General background information may also be of use.  The host may

								also want to do some reading and may be interested in books on wine in

								general or zinfandels in particular.  For example, the host may be

								interested in the books that Amazon.com has for <a href="http://www.amazon.com/exec/obidos/search-handle-url/index=books&amp;field-keywords=zinfandel&amp;search-type=ss&amp;bq=1/103-2905386-5649420">sale</a>

								on zinfandel.   The host may also be interested in information

								concerning wines from the same region, and thus may be interested in Sonoma

								zinfandels.  A wine agent may have typical background information

								available that is related to its main knowledge areas.  For example,

								this wine agent is concerned with matching foods and wines, so it may have

								both free and purchasable information on this topic such as the Wine Spectator's

								article on <a href="http://www.winespectator.com/Wine/Wine_Basics/Wine_Basics_Template/0,1199,17,00.html">matching

								food and wine</a>.

								</p>


								<p>

								The dinner host  may also want to acquire appropriate wine accessories

								prior to the event.  Wine is served in wine glasses and different

								wine varietals are best served in different kinds of glasses.  For

								example, if the host has chosen a meal course  for which a zinfandel

								is appropriate, the host may want to know that <a href="http://www.riedelcrystal.com/index.htm">Riedel</a>

								is a well-known manufacturer of wine glassware.  The host may also

								want to be linked to the Wine Enthusiast (a well respected supplier of

								wine merchandise) and be told that the Wine Enthusiast has <a href="http://www.wineenthusiast.com/shopping/prod_detail/main.asp?cat=GW&amp;catID=2&amp;sl=0&amp;productID=4099&amp;uid=8E539ACF-42AF-4EE4-BB3E-5BB42C28A8BC">Riedel's

								Vinum Zinfandel glass</a> for sale as a set of 4 for $63.95 (with a discount

								to $59.95 if you buy two sets of 4 glasses).   The host may also

								be interested to know that Amazon.com has <a href="http://www.amazon.com/exec/obidos/tg/detail/-/B00006E9SS/qid=1033070213/sr=8-2/ref=sr_8_2/103-2905386-5649420?v=glance&amp;s=home-garden&amp;n=507846">Reidel's

								Sommelier Zinfandel single stem glass</a> available for $49.99 (and claims

								a list price of $65.00).    Amazon also has the same Vinum

								glass for sale in sets of 6 (instead of 4 on the wine enthusiast) for $79.99

								(and claims a list price of $119.40).  A wine agent could provide

								a comparison listing of glassware that is matched to the meal (i.e., is

								appropriate to be used to serve zinfandel) and then is compared by price

								or other criteria chosen from a list of properties in the ontology.

								</p>


								<p>

								The dinner host may want to consider other wine accessories.  From

								the ontology, we know that corkscrews are wine accessories.  The background

								ontology may encode subclasses of corkscrews or such information could

								be found from relevant wine sites as well.     The

								Wine Enthusiast has a set of <a href="http://www.wineenthusiast.com/content/gateway/gateway.asp?cat=CS&amp;uid=8E539ACF-42AF-4EE4-BB3E-5BB42C28A8BC">corkscrews</a>

								they <a href="http://www.wineenthusiast.com/templates/recommend.asp?cat=EE&amp;uid=8E539ACF-42AF-4EE4-BB3E-5BB42C28A8BC">recommend</a>

								(with descriptions of the types and price ranges).  They also distinguish

								corkscrews by type (level, waiter, stationary, twist, and pump) and the

								dinner host may want to get information about those styles.

								</p>


								<p>

								The wine agent may be taken to many levels of sophistication depending

								upon background ontology knowledge of the domain and information and services

								sites.    In this example, we only exploited information

								concerning wines, varietal type, food and wine combinations, some wine

								accessories and their related properties.  We could of course expand

								this to include more information and more constraints by the customer.

								</p>


								<p>An evolving example of this wine agent is <a href="http://www.ksl.stanford.edu/people/dlm/webont/wineAgent/">available.</a>

								</p>


								<hr />


								<h1><a id="Acknowledgements" name="Acknowledgements"></a>

								Acknowledgements

								</h1>


								<p>

								This document is the result of extensive discussions within the

								<a href="http://www.w3.org/2001/sw/WebOnt/">Web Ontology Working Group

								</a>as a whole.  The members of this group working group included:

								Yasser al Safadi, Jean-François Baget, James Barnette,

								Sean Bechhofer, Jonathan Borden, Frederik Brysse, Stephen Buswell,

								Jeremy Carroll, Dan Connolly, Peter Crowther, Jonathan Dale, Jos De Roo,

								David De Roure, Mike Dean, Larry Eshelman,

								Jérôme Euzenat, Dieter Fensel, Tim Finin, Nicholas Gibbins, Sandro

								Hawke Pat Hayes,

								Jeff Heflin, Ziv Hellman, James Hendler, Bernard Horan, Masahiro Hori,

								Ian Horrocks, Francesco Iannuzzelli, Mario Jeckle, Ruediger Klein, Natasha Kravtsova, Ora

								Lassila, Alexander Maedche, Massimo Marchiori, Deborah L. McGuinness,

								Libby Miller, Enrico Motta, Leo Obrst, Laurent Olivry , Peter

								Patel-Schneider, Martin Pike, Marwan Sabbouh, Guus Schreiber,

								Shimizu Noboru, Michael Sintek, Michael Smith, Ned Smith, John Stanton, Lynn

								Andrea Stein, Herman ter Horst, Lynne R. Thompson, David Trastour,

								Frank van Harmelen, Bernard Vatant, Raphael Volz, Evan Wallace, Christopher Welty,

								Charles White and John Yanosy.

								</p>


								<p>

								Some critical early text on complex restrictions was written by

								<a href="http://www.aifb.uni-karlsruhe.de/WBS/rvo/">Raphael Volz</a>,

								Forschungszentrum Informatik (FZI).

								Appendix B was contributed by Guus Schreiber, University of Amsterdam,

								<a href="mailto:schreiber@swi.psy.uva.nl">schreiber@swi.psy.uva.nl</a>.

								Substantial insight was provided by the

								<a href="http://www.w3.org/TR/daml+oil-walkthru/"><em>DAML+OIL Walkthru</em></a>.

								Jeremy Carroll, Jerome Euzenat, Jeff Heflin, Kevin Page and

								Peter F. Patel-Schneider provided extensive reviews.

								At the WG Face to Face, 8 October 2002, Stephen Buswell,

								Ruediger Klein, Enrico Motta, and Evan Wallace provided a detailed review of the

								ontology resulting in substantial changes.

								At the WG Face to Face, 10 January 2003, Jonathan Dale, Bernard Horan,

								Guus Schreiber, and Jeff Heflin provided detailed reviews of the

								Guide resulting in changes.

								</p>


								<!--

								<h1><a id="Notes" name="Notes">Notes</a></h1>


								<dl>

								  <dt><a id="Note-1" name="Note-1"></a>Note 1</dt>

								  <dd>Text.</dd>


								</dl>


								<hr />

								-->


								<hr />


								<h1><a id="Glossary" name="Glossary"></a>

								<a id="OWLGlossary" name="OWLGlossary">OWL Glossary</a></h1>


								<dl>


								<dt>Attribute</dt><dd>as in XML</dd>

								<dt>Class Definition</dt><dd>informal term for an owl:Class element</dd>

								<dt>Class Description</dt><dd>describes an OWL class, either by a class name or

								by specifying a class extension of an unnamed anonymous class

								</dd>

								<dt>Class name</dt><dd>informal term for an owl:Class rdf:ID attribute value.</dd>

								<dt>Class</dt><dd>as in RDF</dd>

								<dt>Component</dt><dd>for parts of a definition e.g. the arguments to intersection-of in a class definition</dd>

								<dt>Concept</dt><dd>informal term for the abstractions "in the world" that ontologies describe</dd>

								<dt>Constraint</dt><dd>informal term for discussing the effect of a restriction</dd>

								<dt>Data-valued Property</dt><dd>alternative term for DataType Property</dd>

								<dt>Datatype Property</dt><dd>an OWL property that relates individuals to data values</dd>

								<dt>Datatype</dt><dd>an RDFS datatype, almost always one of the built-in non-list XML Schema datatypes </dd>

								<dt>Element</dt><dd>(1) as in XML</dd><dd>(2) an element of a set</dd>

								<dt>Entity</dt><dd>as in XML</dd>

								<dt>Imports Closure</dt><dd>the information in an ontology document, plus the information in the imports closure of ontology documents that are imported by the document</dd>

								<dt>Individual-valued Property</dt><dd>alternative term for Object Property </dd>

								<dt>Individual</dt><dd>an instance of an OWL class, i.e., a resource that belongs to the class extension of an OWL class</dd>

								<dt>Instance Of</dt><dd>the relation between an individual and a class</dd>

								<dt>Instance</dt><dd>a member of the class extension of an OWL class</dd>

								<dt>Name</dt><dd>as in XML Namespaces</dd>

								<dt>Named Class</dt><dd>an OWL class with an associated identifier</dd>

								<dt>Node</dt><dd>as in RDF Graphs</dd>

								<dt>OWL Class</dt><dd>an RDFS class that belongs to the class extension of owl:Class</dd>

								<dt>Object Property</dt><dd>an OWL property that relates individuals to other individuals</dd>

								<dt>Object</dt><dd>(1) the object of an RDF triple</dd> <dd>(2) an alternative term for individual (used for historical reasons)</dd>

								<dt>Ontology Document</dt><dd>a Web document that contains an ontology, generally indicated by the presence of an owl:Ontology element in the document</dd>

								<dt>Ontology</dt><dd>(1) collection of information, generally including information about classes and properties</dd><dd>(2) the information contained in an ontology document </dd>

								<dt>Property Definition</dt><dd>informal term for an

								owl:ObjectProperty element and or owl:DatatypeProperty element </dd>

								<dt>Resource</dt><dd>an element of the RDF domain of discourse</dd>

								<dt>Restriction, global</dt><dd>reserved for discussions of the <tt>domain</tt> and <tt>range</tt> of properties</dd>

								<dt>Restriction, local</dt><dd>[see above]</dd>

								<dt>Restriction</dt><dd>usually a piece of a class expression, a statement that expresses a constraint, local by default</dd>

								<dt>Set</dt><dd>a mathematical set</dd>

								<dt>Statement</dt><dd>as in RDF Graphs</dd>

								<dt>Type</dt><dd>as in RDF (rdf:type)</dd>

								<dt>URI reference</dt><dd>as in RDF </dd>

								<dt>Unnamed Class</dt><dd>an OWL class without an associated identifier, normally components of restrictions.</dd>

								<dt>Vocabulary</dt><dd>a set of URI references</dd>


								</dl>


								<br /><br />


								<hr />


								<h1><a id="TermIndexAndCrossReference" name="TermIndexAndCrossReference">

								Term Index and Cross Reference</a></h1>


								<h2><a id="TermIndex" name="TermIndex">Term Index</a></h2>


								<table width="50%">

								<tr><th>Term</th><th>Section</th></tr>


								<tr><td class="index">anonymous class</td>

								    <td class="index"><a href="#term_anonymousClass">3.2.1. </a></td></tr>

								<tr><td class="index">class</td>

								    <td class="index"><a href="#term_class">3.1.3. </a></td></tr>

								<tr><td class="index">cardinality</td>

								    <td class="index"><a href="#term_cardinality">3.4.2. </a></td></tr>

								<tr><td class="index">complement</td>

								    <td class="index"><a href="#term_complement">5.1.3. </a></td></tr>

								<tr><td class="index">datatype</td>

								    <td class="index"><a href="#term_datatype">3.2.1. </a></td></tr>

								<tr><td class="index">datatype property</td>

								    <td class="index"><a href="#term_datatypeproperties">3.2.1. </a></td></tr>

								<tr><td class="index">domain</td>

								    <td class="index"><a href="#term_domain">3.2.1. </a></td></tr>

								<tr><td class="index">entailed</td>

								    <td class="index"><a href="#term_entailed">1. </a></td></tr>

								<tr><td class="index">enumerated</td>

								    <td class="index"><a href="#term_enumerated">5. </a></td></tr>

								<tr><td class="index">extension</td>

								    <td class="index"><a href="#term_extension">3.1. </a></td></tr>

								<tr><td class="index">instance of</td>

								    <td class="index"><a href="#term_instance">3.1.3. </a></td></tr>

								<tr><td class="index">intersectionOf</td>

								    <td class="index"><a href="#term_intersection">5.1.1. </a></td></tr>

								<tr><td class="index">imports</td>

								    <td class="index"><a href="#term_import">2.2. </a></td></tr>

								<tr><td class="index">individual</td>

								    <td class="index"><a href="#term_individual">3.1.3. </a></td></tr>

								<tr><td class="index">instance</td>

								    <td class="index"><a href="#term_instanceOf">3.1.3. </a></td></tr>

								<tr><td class="index">monotonic</td>

								    <td class="index"><a href="#term_monotonic">2. </a></td></tr>

								<tr><td class="index">object properties</td>

								    <td class="index"><a href="#term_objectproperties">3.2.1. </a></td></tr>

								<tr><td class="index">ontology</td>

								    <td class="index"><a href="#term_ontology">1. </a></td></tr>

								<tr><td class="index">open world</td>

								    <td class="index"><a href="#term_openworld">2. </a></td></tr>

								<tr><td class="index">OWL DL</td>

								    <td class="index"><a href="#term_OWLDL">1.1. </a></td></tr>

								<tr><td class="index">OWL Full</td>

								    <td class="index"><a href="#term_OWLFull">1.1. </a></td></tr>

								<tr><td class="index">OWL Lite</td>

								    <td class="index"><a href="#term_OWLLite">1.1. </a></td></tr>

								<tr><td class="index">property</td>

								    <td class="index"><a href="#term_Properties">3.2.1. </a></td></tr>

								<tr><td class="index">range</td>

								    <td class="index"><a href="#term_range">3.2.1. </a></td></tr>


								<tr><td class="index">restriction class</td>

								    <td class="index"><a href="#term_restriction_class">3.4.1. </a></td></tr>


								<tr><td class="index">union</td>

								    <td class="index"><a href="#term_union">5.1.2. </a></td></tr>

								<tr><td class="index">unique names</td>

								    <td class="index"><a href="#term_uniqueName">4.2. </a></td></tr>


								</table>

								<br /><br />


								<h2><a id="CrossReference" name="CrossReference">

								Guide, Reference and Semantics Cross Reference</a>

								</h2>


								<table>

								<tr><th>OWL Guide</th><th>OWL Reference</th><th>OWL Semantics</th></tr>


								<tr><td class="index">

								<a href="#owl_AllDifferent">owl:AllDifferent / 4.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#AllDifferent-def">owl:AllDifferent</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/rdfs.html#owl_AllDifferent_rdf">owl:AllDifferent</a></td></tr>


								<tr><td class="index">

								<a href="#owl_allValuesFrom">owl:allValuesFrom / 3.4.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#allValuesFrom-def">owl:allValuesFrom</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_allValuesFrom_semantics">owl:allValuesFrom</a></td></tr>


								<tr><td class="index">

								<a href="#owl_backwardCompatibleWith">owl:backwardCompatibleWith / 6. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#backwardCompatibleWith-def">owl:backwardCompatibleWith</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/mapping.html#owl_backwardCompatibleWith_mapping">owl:backwardCompatibleWith</a></td></tr>


								<tr><td class="index">

								<a href="#owl_cardinality">owl:cardinality / 3.4.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#cardinality-def">owl:cardinality</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_cardinality_semantics">owl:cardinality</a></td></tr>


								<tr><td class="index">

								<a href="#owl_Class">owl:Class / 3.1.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#Class-def">owl:Class</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_Class_semantics">owl:Class</a></td></tr>


								<tr><td class="index">

								<a href="#owl_complementOf">owl:complementOf / 5.1.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#complementOf-def">owl:complementOf</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_complementOf_semantics">owl:complementOf</a></td></tr>


								<tr><td class="index">

								<a href="#owl_DatatypeProperty">owl:DatatypeProperty / 3.2.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#DatatypeProperty-def">owl:DatatypeProperty</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_DatatypeProperty_semantics">owl:DatatypeProperty</a></td></tr>


								<tr><td class="index">

								<a href="#owl_DeprecatedClass">owl:DeprecatedClass / 6. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#DeprecatedClass-def">owl:DeprecatedClass</a></td><td class="index">

								&nbsp;</td></tr>


								<tr><td class="index">

								<a href="#owl_DeprecatedProperty">owl:DeprecatedProperty / 6. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#DeprecatedProperty-def">owl:DeprecatedProperty</a></td><td class="index">

								&nbsp;</td></tr>


								<tr><td class="index">

								<a href="#owl_differentFrom">owl:differentFrom / 4.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#differentFrom-def">owl:differentFrom</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_differentFrom_semantics">owl:differentFrom</a></td></tr>


								<tr><td class="index">

								<a href="#owl_disjointWith">owl:disjointWith / 5.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#disjointWith-def">owl:disjointWith</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_disjointWith_semantics">owl:disjointWith</a></td></tr>


								<tr><td class="index">

								<a href="#owl_distinctMembers">owl:distinctMembers / 4.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#distinctMembers-def">owl:distinctMembers</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/rdfs.html#owl_distinctMembers_rdf">owl:distinctMembers</a></td></tr>


								<tr><td class="index">

								<a href="#owl_equivalentClass">owl:equivalentClass / 4.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#equivalentClass-def">owl:equivalentClass</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_equivalentClass_semantics">owl:equivalentClass</a></td></tr>


								<tr><td class="index">

								<a href="#owl_equivalentProperty">owl:equivalentProperty / 4.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#equivalentProperty-def">owl:equivalentProperty</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_equivalentProperty_semantics">owl:equivalentProperty</a></td></tr>


								<tr><td class="index">

								<a href="#owl_FunctionalProperty">owl:FunctionalProperty / 3.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#FunctionalProperty-def">owl:FunctionalProperty</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_FunctionalProperty_semantics">owl:FunctionalProperty</a></td></tr>


								<tr><td class="index">

								<a href="#owl_hasValue">owl:hasValue / 3.4.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#hasValue-def">owl:hasValue</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_hasValue_semantics">owl:hasValue</a></td></tr>


								<tr><td class="index">

								<a href="#owl_imports">owl:imports / 2.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#imports-def">owl:imports</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_imports_semantics">owl:imports</a></td></tr>


								<tr><td class="index">

								<a href="#owl_incompatibleWith">owl:incompatibleWith / 6. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#incompatibleWith-def">owl:incompatibleWith</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/mapping.html#owl_incompatibleWith_mapping">owl:incompatibleWith</a></td></tr>


								<tr><td class="index">

								<a href="#owl_intersectionOf">owl:intersectionOf / 5.1.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#intersectionOf-def">owl:intersectionOf</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_intersectionOf_semantics">owl:intersectionOf</a></td></tr>


								<tr><td class="index">

								<a href="#owl_InverseFunctionalProperty">owl:InverseFunctionalProperty / 3.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#InverseFunctionalProperty-def">owl:InverseFunctionalProperty</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_InverseFunctionalProperty_semantics">owl:InverseFunctionalProperty</a></td></tr>


								<tr><td class="index">

								<a href="#owl_inverseOf">owl:inverseOf / 3.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#inverseOf-def">owl:inverseOf</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_inverseOf_semantics">owl:inverseOf</a></td></tr>


								<tr><td class="index">

								<a href="#owl_maxCardinality">owl:maxCardinality / 3.4.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#maxCardinality-def">owl:maxCardinality</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_maxCardinality_semantics">owl:maxCardinality</a></td></tr>


								<tr><td class="index">

								<a href="#owl_minCardinality">owl:minCardinality / 3.4.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#minCardinality-def">owl:minCardinality</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_minCardinality_semantics">owl:minCardinality</a></td></tr>


								<tr><td class="index">

								<a href="#owl_Nothing">owl:Nothing / 3.1.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#Nothing-def">owl:Nothing</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_Nothing_semantics">owl:Nothing</a></td></tr>


								<tr><td class="index">

								<a href="#owl_ObjectProperty">owl:ObjectProperty / 3.2.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#ObjectProperty-def">owl:ObjectProperty</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_ObjectProperty_semantics">owl:ObjectProperty</a></td></tr>


								<tr><td class="index">

								<a href="#owl_oneOf">owl:oneOf / 5.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#oneOf-def">owl:oneOf</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_oneOf_semantics">owl:oneOf</a></td></tr>


								<tr><td class="index">

								<a href="#owl_onProperty">owl:onProperty / 3.4. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#onProperty-def">owl:onProperty</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_onProperty_semantics">owl:onProperty</a></td></tr>


								<tr><td class="index">

								<a href="#owl_Ontology">owl:Ontology / 2.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#Ontology-def">owl:Ontology</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_Ontology_semantics">owl:Ontology</a></td></tr>


								<tr><td class="index">

								<a href="#owl_priorVersion">owl:priorVersion / 6. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#priorVersion-def">owl:priorVersion</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/mapping.html#owl_priorVersion_mapping">owl:priorVersion</a></td></tr>


								<tr><td class="index">

								<a href="#owl_Restriction">owl:Restriction / 3.4. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#Restriction-def">owl:Restriction</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_Restriction_semantics">owl:Restriction</a></td></tr>


								<tr><td class="index">

								<a href="#owl_sameAs">owl:sameAs / 4.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#sameAs-def">owl:sameAs</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_sameAs_semantics">owl:sameAs</a></td></tr>


								<tr><td class="index">

								<a href="#owl_someValuesFrom">owl:someValuesFrom / 3.4.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#someValuesFrom-def">owl:someValuesFrom</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_someValuesFrom_semantics">owl:someValuesFrom</a></td></tr>


								<tr><td class="index">

								<a href="#owl_SymmetricProperty">owl:SymmetricProperty / 3.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#SymmetricProperty-def">owl:SymmetricProperty</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_SymmetricProperty_semantics">owl:SymmetricProperty</a></td></tr>


								<tr><td class="index">

								<a href="#owl_Thing">owl:Thing / 3.1.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#Thing-def">owl:Thing</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_Thing_semantics">owl:Thing</a></td></tr>


								<tr><td class="index">

								<a href="#owl_TransitiveProperty">owl:TransitiveProperty / 3.3. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#TransitiveProperty-def">owl:TransitiveProperty</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_TransitiveProperty_semantics">owl:TransitiveProperty</a></td></tr>


								<tr><td class="index">

								<a href="#owl_unionOf">owl:unionOf / 5.1.2. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#unionOf-def">owl:unionOf</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#owl_unionOf_semantics">owl:unionOf</a></td></tr>


								<tr><td class="index">

								<a href="#owl_versionInfo">owl:versionInfo / 6. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#versionInfo-def">owl:versionInfo</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/mapping.html#owl_versionInfo_mapping">owl:versionInfo</a></td></tr>


								<tr><td class="index">

								rdf:List</td><td class="index">

								rdf:List</td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/rdfs.html#rdf_List_rdf">rdf:List</a></td></tr>


								<tr><td class="index">

								rdf:nil</td><td class="index">

								rdf:nil</td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/rdfs.html#rdf_nil_rdf">rdf:nil</a></td></tr>


								<tr><td class="index">

								<a href="#rdf_type">rdf:type</a></td><td class="index">

								rdf:type</td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#rdf_type_semantics">rdf:type</a></td></tr>


								<tr><td class="index">

								<a href="#rdfs_comment">rdfs:comment / 2.2. </a></td><td class="index">

								rdfs:comment</td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/mapping.html#rdfs_comment_mapping">rdfs:comment</a></td></tr>


								<tr><td class="index">

								<a href="#rdfs_Datatype">rdfs:Datatype / 3.2.2. </a></td><td class="index">

								rdfs:Datatype</td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/rdfs.html#rdfs_Datatype_rdf">rdfs:Datatype</a></td></tr>


								<tr><td class="index">

								<a href="#rdfs_domain">rdfs:domain / 3.2.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#domain-def">rdfs:domain</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#rdfs_domain_semantics">rdfs:domain</a></td></tr>


								<tr><td class="index">

								<a href="#rdfs_label">rdfs:label / 3.1.1. </a></td><td class="index">

								rdfs:label</td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/mapping.html#rdfs_label_mapping">rdfs:label</a></td></tr>


								<tr><td class="index">

								<a href="#rdfs_Literal">rdfs:Literal / 3.3. </a></td><td class="index">

								rdfs:Literal</td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/rdfs.html#rdfs_Literal_rdf">rdfs:Literal</a></td></tr>


								<!--

								<tr><td class="index">

								rdf:Property</td><td class="index">

								rdf:Property</td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/rdfs.html#owl_Property_rdf">rdf:Property</a></td></tr>

								-->

								<tr><td class="index">

								<a href="#rdfs_range">rdfs:range / 3.2.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#range-def">rdfs:range</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#rdfs_range_semantics">rdfs:range</a></td></tr>


								<tr><td class="index">

								<a href="#rdfs_subClassOf">rdfs:subClassOf / 3.1.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#subClassOf-def">rdfs:subClassOf</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#rdfs_subClassOf_semantics">rdfs:subClassOf</a></td></tr>


								<tr><td class="index">

								<a href="#rdfs_subPropertyOf">rdfs:subPropertyOf / 3.2.1. </a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/#subPropertyOf-def">rdfs:subPropertyOf</a></td><td class="index">

								<a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/direct.html#rdfs_subPropertyOf_semantics">rdfs:subPropertyOf</a></td></tr>


								</table>


								<hr />


								<h1><a name="References">References</a></h1>


								<h2><a name="RelatedOWL">Related OWL</a></h2>


								<dl>

								  <dt><a name="Requirements">Requirements</a></dt>

								  <dd>

								    <a href="http://www.w3.org/TR/2003/CR-webont-req-20030818/">

								    <cite>OWL Web Ontology Language Use Cases and Requirements</cite>

								    </a>.

								    Jeff Heflin, ed.

								    W3C Candidate Recommendation, 18 August 2003.

								    <br /><br />

								  </dd>


								  <dt><a name="FeatureList">Overview</a></dt>

								  <dd>

								    <a href="http://www.w3.org/TR/2003/CR-owl-features-20030818/">

								      <cite>OWL Web Ontology Language Overview</cite>

								    </a>.

								    Deborah L. McGuinness and Frank van Harmelen, eds.

								    W3C Candidate Recommendation, 18 August 2003.

								    <br /><br />

								  </dd>


								  <dt><a name="Reference">Reference</a></dt>

								  <dd>

								    <a href="http://www.w3.org/TR/2003/CR-owl-ref-20030818/">

								      <cite>OWL Web Ontology Language Reference</cite>

								    </a>.

								    Mike Dean and Guus Schreiber, eds.

								    W3C Candidate Recommendation, 18 August 2003.

								    <br /><br />

								  </dd>


								  <dt><a name="FormalModel" id="FormalModel">Formal Model</a></dt>

								  <dd>

								    <a href="http://www.w3.org/TR/2003/CR-owl-semantics-20030818/">

								     <cite>OWL Web Ontology Language Semantics and Abstract

								     Syntax</cite>

								   </a>,

								   Peter F. Patel-Schneider, Partick Hayes, and Ian Horrocks, eds.

								   W3C Candidate Recommendation, 18 August 2003.

								   <br /><br />

								 </dd>


								  <dt><a name="TestCases" id="TestCases">Test Cases</a></dt>

								  <dd>

								    <a href="http://www.w3.org/TR/2003/CR-owl-test-20030818/">

								      <cite>OWL Web Ontology Language Test Cases</cite>

								    </a>,

								    Jeremy J. Carroll and Jos De Roo, eds.

								    W3C Candidate Recommendation, 18 August 2003.

								    <br /><br />

								  </dd>


								</dl>

								<br />


								<h2><a name="RelatedStandards">Related W3C Standards</a></h2>


								<dl>


								  <dt><a id="RDF1" name="RDF1">RDF</a></dt>

								  <dd> <a href="http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/">

								   <cite>Resource Description Framework (RDF) Model and Syntax

								                  Specification.</cite></a>

								   World Wide Web Consortium Recommendation, 1999. Lassila, Swick [ed].

								 <br /><br />

								 </dd>


								  <dd> <a id="RDFSemantics" name="RDFSemantics"></a>

								    <a href="http://www.w3.org/TR/rdf-mt/">

								    <cite>RDF Semantics</cite>

								    </a> W3C Working Draft 23 January 2003. Patrick Hayes, ed.

								  <br /><br /></dd>


								  <dd> <a id="RDFSyntax" name="RDFSyntax"></a>

								    <a href="http://www.w3.org/TR/rdf-syntax-grammar/">

								    <cite>RDF/XML Syntax Specification (Revised)</cite>

								    </a> W3C Working Draft 23 January 2003. Dave Beckett, ed.

								  <br /><br /></dd>


								 <dd>

								    <a href="http://www.w3.org/RDF/">RDF: Resource Description Framework</a>.

								    Background at W3C.

								  <br /><br />

								  </dd>


								  <dt><a id="RDFS" name="RDFS">RDFS</a> </dt>

								  <dd> <a href="http://www.w3.org/TR/rdf-schema/">

								    <cite>RDF Vocabulary Description Language 1.0: RDF Schema</cite>

								    </a> W3C Working Draft 23 January 2003. Dan Brickley, R.V. Guha, eds.

								  <br /><br /></dd>


								  <dt><a id="XML1" name="XML1">XML</a> </dt>

								  <dd> <a href="http://www.w3.org/TR/1998/REC-xml-19980210">

									 <cite>Extensible Markup Language (XML) 1.0</cite>.

								  </a>

								  <br /><br />

								  </dd>


								  <dd>

								    <a href="http://www.webreview.com/2000/08_04/webauthors/08_04_00_4.shtml">

								       <cite> XML Tutorial 1: Well-Formed XML Documents</cite></a>.

								       Bonnie SooHoo Aug 4, 2000 in webreview.com.

								  <br /><br />

								  </dd>


								  <dd> <a href="http://www.w3.org/XML/">Extensible Markup Language

								  (XML)</a>. More background at W3C.

								  <br /><br />

								  </dd>


								  <dt><a id="XMLSCHEMA" name="XMLSCHEMA">XML Schema</a></dt>

								  <dd> <a href="http://www.w3.org/XML/Schema">W3C XML Schema</a>   <br /><br />

								</dd>


								  <dt><a id="URI1" name="URI1">URI</a></dt>

								  <dd><a href="http://www.ietf.org/rfc/rfc2396.txt">

								    <cite>Uniform Resource Identifiers (URI): Generic Syntax.</cite>.

									</a> IETF Draft Standard August 1998 (RFC 2396) T. Berners-Lee, R. Fielding, L. Masinter

								   <br /><br />

								</dd>


								  <dd>

								    <a name="URI" id="URI"></a>

								    <a href="http://www.w3.org/Addressing/"> Web Naming and Addressing Overview (URIs, URLs, ...)</a>.

								           More background at W3C.

								  <br /><br />

								  </dd>


								  <dt><a id="XMLNS" name="XMLNS">XML Namespaces</a></dt>

								  <dd>

								    <a href="http://www.w3.org/TR/1999/REC-xml-names-19990114/">

								       <cite>Namespaces in XML</cite></a>. W3C Recommendation Jan 1999.

								  <br /><br />

								  </dd>


								  <dd>

								    <a href="http://www.xml.com/xml/pub/1999/01/namespaces.html"> XML

								    Namespaces by Example</a>. Tim Bray Jan. 19, 1999 in XML.com.

								  <br /><br />

								  </dd>


								  <dd>

								    <a href="http://www.xml.com/pub/2000/03/08/namespaces/index.html">

								    <cite> Namespace Myths Exploded</cite></a>. Ronald Bourret. March 8, 2000 in XML.com.

								  <br /><br />

								  </dd>


								  <dt><a id="XMLBase" name="XMLBase">XML Base</a></dt>

								  <dd> <a href="http://www.w3.org/TR/xmlbase/">XML Base</a>. W3C Recommendation   <br />  <br />

								</dd>


								</dl>

								<br />


								<h2><a name="SampleOntology" id="SampleOntology">Sample Ontologies and

								    Applications</a></h2>


								<dl>


								  <dt><a id="wine1" name="wine1">Daml.org Wine Ontology</a></dt>

								  <dd>

								    <a href="http://www.daml.org/ontologies/76">http://www.daml.org/ontologies/76</a>

								  <br /><br />

								  </dd>


								  <dt><a id="wine4" name="wine4">Wine Ontology / CLASSIC Tutorial</a></dt>

								  <dd>

								    <a href="http://www.bell-labs.com/project/classic/papers/ClassTut/ClassTut.html">

								    <cite>Classic Knowledge Representation System Tutorial</cite>

								    </a>. Deborah L. McGuinness , Peter

								      F. Patel-Schneider , Richmond H. Thomason, Merryll K. Abrahams, Lori Alperin Resnick ,

								      Violetta Cavalli-Sforza, and Cristina Conati.

								       AT&amp;T Bell Laboratories and University of Pittsburgh, 1994.

								  <br /><br />

								  </dd>


								  <dt><a id="wine2" name="wine2">Wine Ontology Tutorial</a></dt>

								  <dd>

								      <a href="http://www.ksl.stanford.edu/people/dlm/papers/ontology-tutorial-noy-mcguinness-abstract.html">

								        <cite>Ontology Development 101: A Guide to Creating Your First Ontology</cite>.

								      </a> Natalya Fridman Noy and Deborah

								           L. McGuinness. Stanford Knowledge Systems Laboratory Technical

								           Report KSL-01-05 and Stanford Medical Informatics Technical Report

								           SMI-2001-0880, March 2001.

								  <br /><br />

								  </dd>


								  <dt><a id="wine3" name="wine3">Wine Ontology in CLASSIC</a></dt>

								  <dd>

								    <a href="http://www.ksl.stanford.edu/people/dlm/papers/living-with-classic-abstract.html">

								    <cite> Living with CLASSIC: When and How to Use a KL-ONE-Like Language</cite>

								    </a>. Ronald J. Brachman, Deborah L. McGuinness , Peter

								      F. Patel-Schneider , Lori Alperin Resnick , and Alex

								      Borgida. in John Sowa, ed.,

								    <em>Principles of Semantic Networks: Explorations in the representation of knowledge</em>,

								       Morgan-Kaufmann: San Mateo, California, 1991, pages 401--456.

								  <br /><br />

								  </dd>


								  <dt><a id="IntegratingApplications" name="IntegratingApplications">Integrating Applications</a></dt>

								  <dd>

								    <a href="http://www.w3.org/2002/07/swint">

								    <cite> Integrating Applications on the Semantic Web</cite>

								    </a>. James Hendler, Tim Berners-Lee, and Eric Miller.

								    <em>Journal of the Institute of

								Electrical Engineers of Japan</em>, Vol 122(10), October, 2002, p. 676-680

								  <br /><br />

								  </dd>


								  <dt><a id="VerticalNet" name="VerticalNet">VerticalNet</a></dt>

								  <dd>


								<a href="http://www.ksl.stanford.edu/people/dlm/papers/ontologyBuilderVerticalNet-abstract.html">

								    <cite>Industrial Strength Ontology Management</cite> </a>. Aseem Das, Wei Wu, and

								Deborah L. McGuinness. Stanford Knowledge Systems Laboratory Technical

								Report KSL-01-09 2001. In the <em>Proceedings of the International

								Semantic Web Working Symposium</em>. Stanford, CA, July 2001

								</dd>

								</dl>


								<br />


								<h2><a name="RelatedKR">Related KR Language Research</a></h2>

								<dl>

								  <dt><a name="DAMLPlusOIL" id="DAMLPlusOIL">DAML+OIL</a></dt>

								  <dd>

								    <a name="DAMLPlusOIL-submission" id="DAMLPlusOIL-submission"/>

								    <a href="http://www.w3.org/Submission/2001/12/">DAML+OIL W3C

								  Submission</a>. Includes reference description, both model theoretic

								  and axiomatic semantics, annotated walkthrough and examples.

								  <br /><br />

								  </dd>

								  <dd>

								    <a name="DAMLPlusOIL-walkthrough" id="DAMLPlusOIL-walkthrough"/>

								    <a href="http://www.W3.org/TR/daml+oil-walkthru/">

								    <cite>Annotated DAML+OIL Ontology Markup</cite></a>.

								  Dan Connolly, Frank van Harmelen, Ian Horrocks, Deborah McGuinness,

								  Peter F. Patel-Schneider, Lynn Andrea Stein. December 2001.

								  <br /><br />

								  </dd>


								  <dt><a id="damlRef" name="damlRef">DAML</a></dt>

								  <dd>

								    <a href="http://www.daml.org">Daml Home Page</a>

								  <br /><br />

								  </dd>


								  <dt><a id="DAML-ONT" name="DAML-ONT"></a>DAML-ONT</dt>

								  <dd>

								    <a href="http://www.daml.org/2000/10/daml-ont.html"> DAML-ONT initial release</a>

								  </dd>

								  <dd><a id="DAML-ONT-KIF">DAML-ONT</a>

								    <a href="http://www.daml.org/2000/10/DAML-Ont-kif-axioms-001107.html">

								       Partial DAML-ONT axiomatization</a> in

								       <a href="http://logic.stanford.edu/kif/kif.html">KIF</a>

								  <br /><br />

								  </dd>


								  <dt><a id="OIL" name="OIL">OIL</a></dt>

								  <dd>

								    <a href="http://oil.semanticweb.org/">OIL Home Page</a>

								  <br /><br />

								  </dd>


								  <dt><a name="SHOE" id="SHOE">SHOE</a></dt>

								  <dd> <a

								  href="http://www.cs.umd.edu/projects/plus/SHOE/">Simple

								  HTML Ontology Extensions (SHOE) home page</a>. University of Maryland.

								  <br /><br />

								  </dd>

								  <dt><a name="XOL" id="XOL">XOL</a></dt>

								  <dd>

								<a href="http://www.ai.sri.com/pubs/full.php?id=676">XOL: An XML-Based

								Ontology Exchange Language</a>.

								Karp, Peter D., Chaudhri, Vinay K. and Thomere, Jerome F.

								Technical Report 559. AI Center, SRI

								International, 333 Ravenswood Ave., Menlo Park, CA 94025, Jul 1999.

								  <br /><br />

								</dd>

								  <dt><a name="OML-CKML" id="OML-CKML"> OML/CKML</a></dt>

								  <dd><a href="http://sern.ucalgary.ca/ksi/kaw/kaw99/papers/Kent1/CKML.pdf">

								The Conceptual Knowledge Framework: OML/CKML</a>.

								Kent, Robert. KAW'99, Twelfth Workshop on Knowledge Acquisition,

								  Modeling and Management, Voyager Inn,

								Banff, Alberta, Canada, October 16-21, 1999.

								<br /><br />

								</dd>


								  <dt><a name="OKBC" id="OKBC"> OKBC</a></dt>


								 <dd>OKBC: A programmatic foundation for knowledge base

								interoperability, V. K. Chaudhri, A. Farquhar, R. Fikes, P. D. Karp,

								and J. P. Rice. In <em>Proceedings of the 15th National Conference on

								Artificial Intelligence (AAAI-98)</em>, pages 600-607. AAAI Press,1998.

								<br /><br /></dd>


								<dt><a name="MCF" id="MCF"> MCF</a></dt>


								<dd><a href="http://www.w3.org/TR/NOTE-MCF-XML/">

								Meta Content Framework Using XML</a>.

								Guha, R.V. and Bray, Tim. Netscape Communications, 6 June 1997.<br/><br/>

								</dd>


								  <dt><a name="DescriptionLogics" id="DescriptionLogics">Description Logics</a></dt>

								  <dd> <a id="dl1" name="dl1"></a>

								      <a href="http://titles.cambridge.org/catalogue.asp?isbn=0521781760">

								  	<cite>The Description Logic Handbook: Theory, Implementation and

								  	Application</cite>.</a>     Franz Baader, Diego Calvanese, Deborah

								      L. McGuinness, Daniele Nardi, and Peter F. Patel-Schneider, editors.

								      Cambridge University Press, 2002.   <br />  <br />

								  </dd>


								  <dd><a id="dl2" name="dl2"></a>

								     <a href="http://dl.kr.org/">Description Logic Web Page</a>


								  <br />  <br />

								  </dd>


								  <dt><a name="KR" id="KR">KR</a></dt>

								  <dd>

								    <a href="http://kr.org/">KR Home Page</a>


								  <br />  <br />

								  </dd>


								</dl>

								<br />


								<h2><a name="RelatedOntology">Related Ontology Research</a></h2>


								<dl>

								  <dt><a id="whatisontology" name="whatisontology">What is Ontology?</a></dt>

								  <dd><a href="http://www.cs.vassar.edu/faculty/welty/papers/fois-intro.pdf">Ontology: Towards a new synthesis</a>.  Barry Smith and Chris Welty.  In, <i>Proceedings of

								the Second International Conference on Formal Ontology in Information Systems</i>

								<a href="http://www.fois.org/">(FOIS-02)</a>. <br />  <br /> </dd>


								  <dt><a id="ontoclean" name="ontoclean">OntoClean Methodology and Ontologies</a></dt>

								  <dd><a href="http://ontology.ip.rm.cnr.it/Ontologies.html">Ontologies and Ontological Engineering</a>  <br />  <br /> </dd>


								  <dt><a name="PartWhole" id="PartWhole">Part Whole Relations</a></dt>

								  <dd><a href="http://ontology.ip.rm.cnr.it/Papers/Parts.pdf">Part-Whole Relations in Object-Centered Systems: an Overview.</a>

								Artale, A., Franconi, E., Guarino, N., and Pazzi, L. In

								<i>Data and Knowledge Engineering</i>, 20(3): 347-383. <br />

								  </dd>


								  <dd>Winston, Chaffin &amp; Herrmann. A Taxonomy of Part-Whole

								    Relations. <em>Cognitive Science</em>, 11:417-444, 1987.

								    <br />  <br />

								  </dd>


								  <dt><a id="Ontoknowledge" name="Ontoknowledge">Ontoknowledge</a></dt>

								  <dd>

								    <a href="http://www.ontoknowledge.org/">Ontoknowledge Home Page</a>

								  <br /><br />

								  </dd>


								  <dt><a name="Ontobroker" id="Ontobroker">Ontobroker</a></dt>

								  <dd><a href="http://ontobroker.aifb.uni-karlsruhe.de/index_ob.html">The

								  Ontobroker home page</a>. Institute AIFB, University of Karlsruhe.

								  <br /><br />

								  </dd>


								  <dt><a name="KAON" id="KAON">KAON</a></dt>

								  <dd>

								    <a href="http://kaon.semanticweb.org">

								      The Karlsruhe Ontology and Semantic Web Tool Suite

								    </a>.

								    <br />

								    <br />

								  </dd>


								</dl>

								<br />


								<h2><a name="General" id="General">General</a></h2>


								<dl>


								  <dt>Dublin Core</dt>


								  <dd><a name="DublinCore" id="DublinCore"/>

								    <a href="http://dublincore.org/">Dublin Core

								    Metadata</a>

								  <br />  <br />

								  </dd>

								  <dd>

									<a href="http://dublincore.org/documents/2001/11/28/dcmes-xml/">

									  <cite>Expressing Dublin Core in RDF/XML</cite>.

									</a>

								  <br />  <br />

								  </dd>


								  <dt><a name="ControlledVocabulary">Controlled Vocabularies</a></dt>


								  <dd>

								      <a href="http://www.digital-web.com/tutorials/tutorial_2002-08.shtml">

								    	<cite>

								  	Mind your phraseology!  Using controlled vocabularies to improve

								  	findability.</cite>

								      </a>

								      <a href="http://www.digital-web.com">DigitalWeb Magazine</a>,

								      Christina Wodtke

								  </dd>

								</dl>

								<br />


								<hr />


								<h1><a id="AppendixA" name="AppendixA">Appendix A</a>: XML + RDF Basics</h1>


								<div class="description">

								    This appendix provides links to introductions to the standards that

								    OWL depends on.</div>


								<p>

								    To fully understand the OWL syntax and semantics you should be

								    familiar with the basics of the  related W3C and IETF standards listed

								    below. A minimal guide to XML and RDF is provided by the first two

								    links below.

								</p>


								<ul>

								  <li><a href="http://kaon.semanticweb.org/Members/rvo/WebOnt_Guide/owlbasics/">

									Fundamentals Overview</a></li>

								  <li><a href="http://www.daml.org/2001/03/daml+oil-walkthru.html#xml-guide">

								        Appendix</a> to the <a href="#DAMLPlusOIL-walkthrough">

								      <em>DAML+OIL Walkthru</em></a><br /><br /></li>


								  <li><a href="http://www.ietf.org/rfc/rfc2396.txt">URI - Uniform Resource Identifier</a> </li>

								  <li><a href="http://www.w3.org/XML/">XML - eXtensible Markup Language</a></li>

								  <li><a href="http://www.w3.org/TR/REC-xml-names/">XML Namespaces</a> </li>

								  <li><a href="http://www.w3.org/XML/Schema">XML Schema</a></li>

								  <li><a href="http://www.w3.org/TR/REC-rdf-syntax/">RDF - Resource Description Framework</a> </li>

								  <li><a href="http://www.w3.org/TR/rdf-schema/">RDF Schema</a> </li>

								</ul>


								<hr />


								<h1><a id="AppendixB" name="AppendixB">Appendix B</a>: History</h1>


								<p>

								<a href="#RDF1">The Resource Description Framework (RDF)</a> was the

								first language specified by the W3C for representing semantic

								information about arbitrary resources.  <a href="#RDFS">RDF Schema

								(RDFS)</a> is a W3C candidate recommendation for an extension to RDF

								to describe RDF vocabularies.  RDFS can be used to create ontologies,

								but it is purposefully lightweight, with less expressive power than

								OWL.

								</p>


								<p>

								Like OWL, RDFS includes classes and properties, as well as range and

								domain constraints on properties.  It provides inheritance hierarchies

								for both classes and properties.  Upon its release users began

								requesting additional features, including data types, enumerations and

								the ability to define properties more rigorously.

								</p>


								<p>

								Other efforts in the research community were already examining exactly

								these sorts of features.  For those who wish to delve more deeply into

								this background, a partial list of projects and languages includes:

								</p>


								<ul>

								<li><a href="#damlRef">DAML - DARPA Agent Markup Language</a></li>

								<li><a href="#DAML-ONT">DAML-ONT</a>  </li>

								<li><a href="#MCF">MCF - Meta Content Framework</a>.</li>

								<li><a href="#Ontobroker">Ontobroker</a></li>

								<li><a href="#Ontoknowledge">On-To-Knowledge</a></li>

								<li><a href="#OIL">OIL - Ontology Inference Layer</a></li>

								<li><a href="#SHOE">SHOE - Simple HTML Ontology Extensions</a></li>

								<li><a href="#XOL">XOL</a></li>

								</ul>


								<p>

								Instead of continuing with separate ontology languages for the

								Semantic Web, a group of researchers, including many of the main

								participants in both the OIL and DAML-ONT efforts, got together in the

								<a href="http://www.daml.org/committee/">Joint US/EU ad hoc Agent

								Markup Language Committee</a> to create a new Web ontology language.

								This language <a href="#DAMLPlusOIL">DAML+OIL</a> built on both OIL and

								DAML-ONT, was <a href="#DAMLPlusOIL-submission">submitted</a> to the

								W3C as a proposed basis for OWL, and was subsequently selected as the

								starting point for OWL.

								</p>


								<p>

								In addition to ontology languages, various taxonomies and existing

								ontologies are already in use commercially. In

								e-Commerce sites they facilitate machine-based

								communication between buyer and seller, enable vertical integration of

								markets and allow descriptions to be reused in different marketplaces.

								Examples of sites that are actually making commercial use ontologies

								include:

								</p>


								<ul>

								<li><a href="#VerticalNet">VerticalNet</a>

								     Vertical Net currently hosts 59 industry-specific e-marketplaces

								     that span diverse industries such as manufacturing,

								     communications, energy, and healthcare.</li>

								</ul>


								<p>

								Various medical or drug-related ontologies have been developed to help

								manage the overwhelming mass of current medical and biochemical research data

								that can be difficult to tie together into a cohesive whole.

								One major resource is the <a href="http://www.geneontology.org/">Gene

								Ontology Consortium</a> which is defining ontologies for

								</p>


								<ul>

								<li>Molecular Function,</li>

								<li>Biological Process, and</li>

								<li>Cellular Components.</li>

								</ul>


								<p>

								That site also has pointers to ontologies for

								</p>


								<ul>

								<li> sequence attributes, </li>

								<li> gene product attributes, </li>

								<li> chemical substances,</li>

								<li>  pathways, </li>

								<li> anatomies, </li>

								<li> pathology, </li>

								<li> physical characteristics, </li>

								<li> experiment attributes, </li>

								<li> classification, and </li>

								<li> pathology. </li>

								</ul>


								<p> There exist large taxonomies in use today that would be ripe for

								extension into the OWL space.  For example, the North American

								Industry Classification System (NAICS) defines a hierarchy of over

								1900 items that identify industry types.

								NAICS is also tied to the International Standard Industrial

								Classification System (ISIC, Revision 3), developed and maintained by

								the United Nations.

								</p>


								<hr />


								<h1><a id="AppendixC" name="AppendixC">Appendix C: An Alternative Region Ontology</a></h1>


								<p>

								This example was developed by Guus Schrieber

								[<a href="http://lists.w3.org/Archives/Public/www-webont-wg/2002Aug/0196.html">

								W3C WG Archive</a>] and presents a more elaborate wine region ontology.

								</p>

								<p>

								For wine the "production area" is an important feature. There is

								enormous variation between wine types with respect to the grain size of the

								production area, ranging from a complete country to a particular vineyard.

								One could distinguish four types of production areas:

								</p>

								<ol>

								<li>country: e.g., France, Italy</li>

								<li>region: e.g., Bordeaux, Medoc, Tuscany, </li>

								<li>town: e.g., Margaux, Montalcino, Montepulciano</li>

								<li>vineyard, e.g., Chateau Margaux, Avignonesi</li>

								</ol>


								<p>

								In addition, we need to model part-of relationships between the

								various sorts of production areas:

								</p>

								<ul>

								<li>regions are part of countries: Tuscany lies in  Italy</li>

								<li>regions may have subregions: the Medoc region is a subpart of the

								  Bordeaux region</li>

								<li>towns are located in regions: Montalcino is located in Tuscany</li>

								<li>vineyards are located in towns: Chateau Margaux is a vineyard in

								  Margaux, Avignonesi in Montepulciano </li>

								</ul>


								<p>

								We would like to be able to derive from our wine KB that a wine from

								Chateau Margaux is a French wine and that Avignonesi is a Tuscan

								wine.

								</p>


								<p>

								<b>MODELING DECISION</b>: at this point we decided to drop the "town"

								subclass and treat towns as regions. This simplifies the model and is

								consistent with the fact that a "town" as a wine production area

								typically stands for an area surrounding the town, which can be larger

								or smaller than the actual town area. For example, the production

								area "Montalcino" is in fact a subregion of Tuscany surrounding the

								village of Montalcino.

								</p>

								<p>

								This leads to the following model:

								</p>

								<h4><a id="AppendixCClasses" name="AppendixCClasses">Classes:</a></h4>


								<pre>

								&lt;owl:Class rdf:ID="&amp;vin;ProductionArea"/ &gt;

								&lt;owl:Class rdf:ID="&amp;vin;Country"&gt;

								    &lt;rdfs:subClassOf rdf:resource="&amp;vin;ProductionArea"/&gt;

								&lt;/owl:Class&gt;

								&lt;owl:Class rdf:ID="&amp;vin;Region"&gt;

								    &lt;rdfs:subClassOf rdf:resource="&amp;vin;ProductionArea"/&gt;

								&lt;/owl:Class&gt;

								&lt;owl:Class rdf:ID="&amp;vin;Vineyard"&gt;

								    &lt;rdfs:subClassOf rdf:resource="&amp;vin;ProductionArea"/&gt;

								&lt;/owl:Class&gt;


								</pre>


								<h5>Triples</h5>


								<pre>

								vin:ProductionArea rdf:type rdfs:Class.

								vin:Country rdfs:subClassOf vin:ProductionArea.

								vin:Region rdfs:subClassOf vin:ProductionArea.

								vin:Vineyard rdfs:subClassOf vin:ProductionArea.

								</pre>


								<h4><a id="AppendixCProperties" name="AppendixCProperties">Properties:</a>

								</h4>


								<pre>

								&lt;owl:ObjectProperty rdf:ID="&amp;vin;hasSubArea"&gt;

								  &lt;rdf:type rdf:resource="&amp;owl;TransitiveProperty" /&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="&amp;vin;subAreaOf"&gt;

								    &lt;owl:inverseOf rdf:resource="&amp;vin;hasSubArea"/&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="&amp;vin;hasRegion"&gt;

								    &lt;rdfs:subPropertyOf rdf:resource="&amp;vin;hasSubArea"/&gt;

								    &lt;owl:domain rdf:resource="&amp;vin;Region"/&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="&amp;vin;regionOf"&gt;

								    &lt;rdf:type rdf:resource="&amp;owl;FunctionalProperty" /&gt;

								    &lt;owl:inverseOf rdf:resource="&amp;vin;hasRegion"/&gt;

								    &lt;owl:range rdf:resource="&amp;vin;Region"/&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="&amp;vin;hasSubRegion"&gt;

								    &lt;rdfs:subPropertyOf rdf:resource="&amp;vin;hasSubArea"/&gt;

								    &lt;owl:range rdf:resource="&amp;vin;Region"/&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="&amp;vin;subRegionOf"&gt;

								    &lt;owl:inverseOf rdf:resource="&amp;vin;hasSubRegion"/&gt;

								    &lt;owl:range rdf:resource="&amp;vin;Region"/&gt;

								    &lt;rdf:type rdf:resource="&amp;owl;FunctionalProperty" /&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="&amp;vin;hasVineyard"&gt;

								    &lt;rdfs:subPropertyOf rdf:resource="&amp;vin;hasSubArea"/&gt;

								    &lt;owl:range rdf:resource="&amp;vin;Vineyard"/&gt;

								&lt;/owl:ObjectProperty&gt;


								&lt;owl:ObjectProperty rdf:ID="&amp;vin;vineyardRegion"&gt;

								    &lt;owl:inverseOf rdf:resource="&amp;vin;hasVineyard"/&gt;

								    &lt;owl:range rdf:resource="&amp;vin;Region"/&gt;

								    &lt;rdf:type rdf:resource="&amp;owl;FunctionalProperty" /&gt;

								&lt;/owl:ObjectProperty&gt;

								</pre>


								<h5>Triples</h5>


								<pre>

								vin:hasSubArea rdf:type rdf:Property.

								vin:hasSubArea rdf:type owl:TransitiveProperty.

								vin:subAreaOf owl:inverseOf vin:hasSubArea.


								vin:hasRegion rdfs:subPropertyOf vin:hasSubArea.

								vin:hasRegion owl:range vin:Region.

								vin:regionOf owl:inverseOf vin:hasRegion.

								vin:regionOf owl:range vin:Country.

								vin:regionOf rdf:type  owl:FunctionalProperty


								vin:hasSubRegion rdfs:subPropertyOf vin:hasSubArea.

								vin:hasSubRegion owl:range vin:Region.

								vin:subRegionOf owl:inverseOf vin:hasSubRegion.

								vin:subRegionOf owl:range vin:Region.

								vin:subRegionOf rdf:type  owl:FunctionalProperty


								vin:hasVineyard rdfs:subPropertyOf vin:hasSubArea.

								vin:hasVineyard owl:range vin:Vineyard.

								vin:vineyardRegion owl:inverseOf vin:hasVineyard..

								vin:vineyardRegion owl:range vin:Region.

								vin:vineyardRegion rdf:type  owl:FunctionalProperty

								</pre>


								<p>

								<b>ONTOLOGICAL NOTE</b>: the part-whole relationship described here is

								well-known in the formal-ontology literature. The typology of

								part-whole relations by <a href="#PartWhole">Winston et al.</a> characterizes this as a

								"place-area" relation. Various authors have criticized and amended this

								typology. If the formal-ontology community would at some point be

								able to make a part-whole typology available in OWL, the properties in

								this wine ontology could be linked to it.

								</p>


								<p>

								<a name="UMLSyntaxExample" id="UMLSyntaxExample"><b>UML NOTE</b></a>:

								Below is a UML class diagram for this example. The modeling decisions

								for this diagram will be discussed in the forthcoming document on the

								UML presentation syntax. For the moment, note the use of the UML

								"composition" construct (the darkened diamond), which caries some of

								the semantics of the place-area relation.

								</p>


								<p>

								<img src="owl-production-area.jpg"

								     alt="Owl Production Area UML Diagram" />

								</p>


								<hr />


								<h1><a id="AppendixD" name="AppendixD">Appendix D: Change Log Since Last Call Release</a></h1>


								<ul>

								 <li>Replaced several references to the "wine ontology" with "wine and food ontology".</li>

								 <li>Added food.owl to entity and namespace definitions.</li>

								 <li>Fixed occurrence of 'hasClass' in food.owl.</li>

								 <li>Added example of <tt>owl:ObjectProperty</tt> <tt>course</tt> from food.owl. </li>

								 <li>Added the <tt>owl:ObjectProperty</tt> <tt>madeFromFruit</tt>

								     and the class <tt>juice</tt> to food.owl.</li>

								 <li>Added xml:base to namespace declaration.</li>

								 <li>Added text re utility of using entities in namespace declarations.</li>

								 <li>Added text qualifying 'typical' nature of header example re w3.org.</li>

								 <li>Wine.owl: Eliminated duplicate restriction on wine.</li>

								 <li>Food.owl: Changed base range of hasDrink to PotableLiquid.</li>

								 <li>Changed "sameIndividualAs always be used, as it is more

								        informative and reduces the likeliehood of mistakes" to

								        "sameIndividualAs be used, as it more clearly states the

									user's intention."</li>

								 <li>Added text re required support for <tt>xsd:integer</tt>

								     and <tt>xsd:string</tt> datatypes.</li>

								 <li>Fixed <tt>owl:versionInfo</tt> in cross reference to indicate

								     section 6., not 5.1.2.</li>

								 <li>Rewrote the second sentence of 3.4.1, which used "instance" 3

								      times to clarify.</li>

								 <li>Deleted Class Expression from Glossary.  Adding Class Description.</li>

								 <li>Wine and food.owl: Added xml:base.</li>

								 <li>Deleted OWL Property from Glossary.</li>

								 <li>In 1.1 Added text re migrating from RDF to OWL DL or OWL Lite.</li>

								 <li>In 1.1 Added more words re the computational properties of Lite

								 and DL. </li>

								 <li>In 1. Added Roadmap xref.</li>

								 <li>Deleted owl:sameIndividualAs and some associated text.</li>

								 <li>In 2.3 added pointer to security and preference solutions. </li>

								 <li>Modifed ontologies. Changed extension from ".owl"

								 to ".rdf" (since we  did not register the owl MIME type). </li>

								 <li>Changed Guide reference "owl.owl" to "owl" in imports discussion. </li>

								 <li>Modifed ontologies. Removed extensions in imports. </li>

								 <li>Modifed food ontologies. Added owl:imports of wine.rdf to

								 food.rdf so that wine properties in food were typed properly. </li>

								 <li>Modifed ontologies. Replaced owl:sameIndividualAs

								 with owl:sameAs. </li>

								 <li>Changed Guide to correspond to ontology modificatons.</li>

								 <li>RDF references updated.</li>

								 <li>Modifed ontologies. Changed doctype to rdf:RDF.</li>

								</ul>


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