pal gov.tutorial2.session7

1PalGov © 2011 1PalGov © 2011

أكاديمية الحكومة اإللكترونية الفلسطينيةThe Palestinian eGovernment Academy

www.egovacademy.ps

Session 7

OWL (Web Ontology Langauge)

Tutorial II: Data Integration and Open Information Systems

Dr. Mustafa Jarrar

University of Birzeit

[email protected]

www.jarrar.info

mailto:[email protected]

http://www.jarrar.info/


About

This tutorial is part of the PalGov project, funded by the TEMPUS IV program of the

Commission of the European Communities, grant agreement 511159-TEMPUS-1-

2010-1-PS-TEMPUS-JPHES. The project website: www.egovacademy.ps

University of Trento, Italy

University of Namur, Belgium

Vrije Universiteit Brussel, Belgium

TrueTrust, UK

Birzeit University, Palestine

(Coordinator )

Palestine Polytechnic University, Palestine

Palestine Technical University, PalestineUniversité de Savoie, France

Ministry of Local Government, Palestine

Ministry of Telecom and IT, Palestine

Ministry of Interior, Palestine

Project Consortium:

Coordinator:

Dr. Mustafa Jarrar

Birzeit University, P.O.Box 14- Birzeit, Palestine

Telfax:+972 2 2982935 [email protected]

http://www.egovacademy.ps/


© Copyright Notes

Everyone is encouraged to use this material, or part of it, but should

properly cite the project (logo and website), and the author of that part.

No part of this tutorial may be reproduced or modified in any form or by

any means, without prior written permission from the project, who have

the full copyrights on the material.

Attribution-NonCommercial-ShareAlike

CC-BY-NC-SA

This license lets others remix, tweak, and build upon your work non-

commercially, as long as they credit you and license their new creations

under the identical terms.

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Tutorial Map

Topic h

Session 1: XML Basics and Namespaces 3

Session 2: XML DTD’s 3

Session 3: XML Schemas 3

Session 4: Lab-XML Schemas 3

Session 5: RDF and RDFs 3

Session 6: Lab-RDF and RDFs 3

Session 7: OWL (Ontology Web Language) 3

Session 8: Lab-OWL 3

Session 9: Lab-RDF Stores -Challenges and Solutions 3

Session 10: Lab-SPARQL 3

Session 11: Lab-Oracle Semantic Technology 3

Session 12_1: The problem of Data Integration 1.5

Session 12_2: Architectural Solutions for the Integration Issues 1.5

Session 13_1: Data Schema Integration 1

Session 13_2: GAV and LAV Integration 1

Session 13_3: Data Integration and Fusion using RDF 1

Session 14: Lab-Data Integration and Fusion using RDF 3

Session 15_1: Data Web and Linked Data 1.5

Session 15_2: RDFa 1.5

Session 16: Lab-RDFa 3

Intended Learning Objectives

A: Knowledge and Understanding

2a1: Describe tree and graph data models.

2a2: Understand the notation of XML, RDF, RDFS, and OWL.

2a3: Demonstrate knowledge about querying techniques for data

models as SPARQL and XPath.

2a4: Explain the concepts of identity management and Linked data.

2a5: Demonstrate knowledge about Integration &fusion of

heterogeneous data.

B: Intellectual Skills

2b1: Represent data using tree and graph data models (XML &

RDF).

2b2: Describe data semantics using RDFS and OWL.

2b3: Manage and query data represented in RDF, XML, OWL.

2b4: Integrate and fuse heterogeneous data.

C: Professional and Practical Skills

2c1: Using Oracle Semantic Technology and/or Virtuoso to store

and query RDF stores.

D: General and Transferable Skills2d1: Working with team.

2d2: Presenting and defending ideas.

2d3: Use of creativity and innovation in problem solving.

2d4: Develop communication skills and logical reasoning abilities.


Session ILOs

After completing this session students will

be able to:

- Understand the notation of OWL.

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Reading Material

OWL Guide

http://www.w3.org/TR/2004/REC-owl-guide-20040210/#BasicDefinitions

You only need to read:Section 1. Introduction

Section 2. The Structure of Ontologies

Section 3. Basic Elements

Section 4. Ontology Mapping

Section 5. Complex Classes

OWL 2 Web Ontology Language: Structural Specification and

Functional-Style Syntax

http://www.w3.org/2007/OWL/draft/owl2-syntax

OWL 2 Document Overview

http://www.w3.org/TR/owl2-overview/

http://www.w3.org/TR/2004/REC-owl-guide-20040210/














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What is OWL?

OWL stands for Web Ontology Language.

OWL is built on top of RDF.

OWL is written in XML.

OWL is for processing information on the web.

OWL was designed to be interpreted by computers.

OWL was not designed for being read by people.

OWL has three sublanguages (OWL full, OWL DL, OWL Lite)

OWL is a W3C standard.

http://www.w3schools.com

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OWLSource: www.w3.org

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What is an Ontology

• Ontology is about the exact description of things and their

relationships.

• For the web, ontology is about the exact description of web

information and relationships between them.

• (only at this stage), you can see an ORM schema as

ontology.

• Later, we will study the difference between an ontology

and a databases schema.

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Why OWL ?

• OWL is part of the "Semantic Web Vision"

– Web information has exact meaning.

– Web information can be processed by computers.

– Computers can integrate information from the web.

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OWL was Designed for Processing Information

• OWL was designed to provide a common way to process

the content of web information (instead of displaying it).

• OWL read by computer applications (instead of humans).

was designed to be

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OWL is Different from RDF

• OWL and RDF Schema are much of the same thing, but

OWL allow constrains and rules.

• OWL comes with a larger vocabulary and stronger syntax

than RDF and RDFS.

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Variations of OWL

• OWL Full – An extension of RDF

– Allows for classes as instances, modification of RDF and OWL

vocabularies

• OWL DL– The part of OWL Full that is in the Description Logic framework.

– Known to have decidable reasoning.

• OWL Lite– A subset of OWL DL

– Easier for frame-based tools to transition to

– Easier reasoning

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OWL is Written in XML

• OWL is specified in XML so it can be easily exchanged between

different types of computers using different types of operating system

and application languages.

• OWL can be seen as an extension of RDF/RDFS, so that RDF

parsers can parse OWL.

• Names in OWL are RDF URI references

– e.g., http://cohse.semanticweb.org/ontologies/people#pet

– Often (informally) abbreviated via XML qualified names

– e.g., pp:pet

• Data items belong to XML Schema datatypes

– e.g., XML Schema integers and strings

– Generally written in RDF/XML form

– e.g., .7.8sd:integer, .Susan.8sd:string

http://cohse.semanticweb.org/ontologies/people

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OWL is a Web Standard

• OWL became a W3C (World Wide Web Consortium) Recommendation

in February 2004.

• A W3C Recommendation is understood by the industry and the web

community as a web standard. A W3C Recommendation is a stable

specification developed by a W3C Working Group and reviewed by the

W3C Membership.

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OWL 2

• OWL 2, became a W3C recommendation in 27 October 2009.

• An ontology language for the semantic Web which is extended from

OWL 1 and empowered by new features.

• OWL 2 DL underpinning description logic is SROIQ DL.

• Contains the majority of constructs to be used for building any needed

ontology.

• OWL 2 is supported by several semantic reasoners such as RacerPro

2, Pellet, Hermit and FaCT++.

• OWL 2 ontologies are primary exchanged as RDF documents, where

these ontologies can be used with information written in RDF.

• OWL 2 elements are identified by Internationalized Resource

Identifiers (IRIs).

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Variations of OWL 2

• OWL 2 EL– Allows for subclass axioms with intersection, existential quantification, top,

bottom and closed classes with only one member.

– Disallow for negation, disjunction, arbitrary universal quantification, role

inverses.

• OWL 2 QL– Allows for subproperties, domain, range and subclass statements.

– Disallow for closed classes.

• OWL 2 RL– Allows for all axiom types, cardinality restrictions(only ≤1 and ≤0 on right

hand side) and closed classes with only one member.

– Disallow certain constructors( universal and negation on left hand side and

extensional and union on right hand side of subclass statements).

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OWL Basics

• Classes

• Individuals

• Properties

• Special Classes and Properties

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Classes

Owl:Class

• Unary predicates: Person(__), City(__).

• User-defined classes which are subclasses of root class owl:Thing. A

class may contain individuals, which are instances of the class, and

other subclasses.

<owl:Class rdf:ID=“Person"/> <owl:Class rdf:ID=“City"/> <owl:Class rdf:ID=“Country"/> <owl:Class rdf:ID=“Book"/>

• Similar to Object-Type in ORM, Entity in EER, or Class in UML

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Individuals

Individuals

• Constants: Edward_Said, Palestine.

• An individual is a member/instance of a class

<Man rdf:ID=“Edward_Said" /><Country rdf:ID=“Palestine" /><City rdf:ID=“Jerusalem" />

• Notice that there is no way in ORM/UML/EER to add instance of concepts as art of the schema.

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Properties

owl:ObjectProperty

• A relation between instances of two classes.

• Binary predicates (author(__, __) ).

• Similar to a binary relation in ORM between two entities.

<owl:ObjectProperty rdf:ID=“Author">

<rdfs:domain rdf:resource="# Book"/>

<rdfs:range rdf:resource="#Person"/>

</owl:ObjectProperty>

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Properties

owl:DataTypeProperty

• Relation between instances of classes and literals.

• The range of a literal datatype (use XML Schema datatypes).

• Similar to a binary relation in ORM between an Entity and a Value.

<owl:DatatypeProperty rdf:ID=“Title">

<rdfs:domain rdf:resource="#Book" />

<rdfs:range rdf:resource=" xsd:string"/>

</owl:DatatypeProperty>

<owl:DatatypeProperty rdf:ID=“Price">

<rdfs:domain rdf:resource="#Book" />

<rdfs:range rdf:resource="xsd:integer"/>

</owl:DatatypeProperty>

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Special Classes and Properties

• Top class: T

owl:Thingcontains all individuals of the domain.

• Bottom class: ┴

owl:Nothingcontains no individuals(empty class).

• Universal property: U

owl:topObjectPropertylinks every individual to every individual.

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Class Expression Axioms

• Subclass Axioms

• Equivalent Classes

• Disjoint Classes

• Disjoint Union of Class Expressions

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rdfs:subClassOf

• Notice that rdfs:subClassOf is part of RDFS, not OWL. This to show

that OWL extends RDF/RDFS.

• rdfs:subClassOf is similar to the SubType relation UML and EER, and

the same as subType in ORM, but here it is not a proper subtypes.

• Similar to a subtype in ORM.

• SubClassOf( a:Man a:Person ) means that Each Man is a Person.

<owl:Class rdf:ID=“Man">

<rdfs:subClassOf rdf:resource=“#Person"/>...

</owl:Class>

<owl:Class rdf:ID=“Book"> <rdfs:subClassOf rdf:resource="#Publication" /> ...

</owl:Class>


Subclass Axioms

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Equivalent Classes

owl:equivalentClass

• States the equivalence (in terms of their class extension) of two named

classes.

• Useful when integrating or mapping between two different ontologies.

<owl:Class rdf:about="#Palestine_President">

<owl:equivalentClass rdf:resource=“aa:PrincipalResidentOfPlestine"/>

</owl:Class>

• A class axiom may contain (multiple) owl:equivalentClass

statements.

<owl:Class rdf:about="#Being">

<owl:equivalentClass rdf:resource="#Human"/>

<owl:equivalentClass rdf:resource="#Person"/>

</owl:Class>

The classes Being, Human and Person are semantically equivalent to each other.

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Disjoint Classes

owl:disjointWith

• Each owl:disjointWith statement asserts that the class extensions of

the two class descriptions involved have no individuals in common.

• DisjointClasses (C1 ... Cn ): all of the classes Ci, 1 ≤ i ≤ n, are pairwise

disjoint; that is, no individual can be at the same time an instance of

both Ci and Cj for i ≠ j.

<owl:Class rdf:about="#Opera">

<rdfs:subClassOf rdf:resource="#MusicDrama"/>

</owl:Class>

<owl:Class rdf:about="#Operetta">

<rdfs:subClassOf rdf:resource="#MusicDrama"/>

<owl:disjointWith rdf:resource="#Opera"/>

</owl:Class>

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Disjoint Classes (continued )

owl:AllDisjointClasses

In order to assert that a set of classes is mutually disjoint, we can use

AllDisjointClasses.

<rdf:Description>

<rdf:type rdf:resource="&owl:AllDisjointClasses"/>

<owl:members rdf:parseType="Collection">

<rdf:Description rdf:about="#Building"/>

<rdf:Description rdf:about="#Tree"/>

<rdf:Description rdf:about="#Bird"/>

</owl:members>

</rdf:Description>

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Disjoint Union of Class Expressions

owl:disjointUnionOf

• DisjointUnion (C C1 ... Cn ): a class C is a disjoint union of the classes

Ci, 1 ≤ i ≤ n, all of which are pairwise disjoint the extensions of all Ci

exactly cover the extension of C.

• DisjointUnion (Person Female Male ) means each Person is either a

Male or a Female, each Female is a Person, each Male is a Person,

and nothing can be both a Female and a Male.

<owl:Class rdf:about="#Person">

<owl:disjointUnionOf rdf:parseType="Collection">

<rdf:Description rdf:about="#Female"/>

<rdf:Description rdf:about="#Male"/>

</owl:disjointUnionOf>

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OWL2 Example1

• In what follows we illustrate a simple example represented in ORM and OWL 2.

• In the example, the illustrated OWL 2 constructs are Class, Subclass, Union of

Classes and Disjoint Classes.

Female

Person

Male

...

<Class rdf:about="&OWL2Example1:Person“/>

<Class rdf:about="&OWL2Example1:Female">

<rdfs:subClassOf rdf:resource="&OWL2Example1:Person"/>

<disjointWith rdf:resource="&OWL2Example1:Male"/>

</Class>

<Class rdf:about="&OWL2Example1:Male">

<rdfs:subClassOf rdf:resource="&OWL2Example1:Person"/>

</Class>

<Class rdf:about="&OWL2Example1:Person">

<equivalentClass>

<Class>

<unionOf rdf:parseType="Collection">

<rdf:Description rdf:about="&OWL2Example1:Female"/>

<rdf:Description rdf:about="&OWL2Example1:Male"/>

</unionOf>

</Class>

<equivalentClass></Class>

…

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Object Property Axioms

• Object Subproperties

• Equivalent Object Properties

• Disjoint Object Properties

• Inverse Object Properties

• Object Property Domain

• Object Property Range

• Functional Object Properties

• Inverse-Functional Object Properties

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Object Subproperties

rdfs:subPropertyOf

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

• SubObjectPropertyOf (OP1 OP2 ): if an individual x is connected by

OP1 to an individual y, then x is also connected by OP2 to y.

• The rdfs:subPropertyOf means that anything with a Borrows property

with value X also has a ChecksOut property with value X.

• Similar to the Subset constraint in ORM.

<owl:ObjectProperty rdf:ID=“Borrows">

<rdfs:domain rdf:resource="#Person"/>

<rdfs:range rdf:resource="#Book"/>


<owl:ObjectProperty rdf:ID=“ChecksOut">

<rdfs:subPropertyOf rdf:resource="# Borrows" />

<rdfs:range rdf:resource="#Book" />

...


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Equivalent Object Properties

owl:equivalentProperty

• EquivalentObjectProperties (OP1 ... OPn): all of the object properties

OPi, 1 ≤ i ≤ n, are semantically equivalent to each other.

• Similar to the Equality constraint in ORM.

• EquivalentObjectProperties (a:hasBrother a:hasMaleSibling) means

that having a brother is the same as having a male sibling.

<owl:ObjectProperty rdf:about="#hasBrother">

<owl:equivalentProperty rdf:resource="#hasMaleSibling"/>


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Disjoint Object Properties

owl:propertyDisjointWith

• DisjointObjectProperties (OP1 ... OPn): all of the object properties

OPi, 1 ≤ i ≤ n, are pairwise disjoint; that is, no individual x can be

connected to an individual y by both OPi and OPj for i ≠ j .

• Similar to the Exclusion constraint in ORM.

• DisjointObjectProperties( a:hasFather a:hasMother ) means that

Fatherhood is disjoint with motherhood.

<owl:ObjectProperty rdf:about="#hasFather">

<owl:propertyDisjointWith rdf:resource="#hasMother"/>


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Inverse Object Properties owl:inverseOf• If a property P is tagged as the owl:inverseOf Q, then for all x and y:

P(x,y) iff Q(y,x).

• Note that the syntax for owl:inverseOf takes a property name as an

argument. A iff B means (A implies B) and (B implies A).

• InverseObjectProperties (OP1 OP2): the object property OP1 is an

inverse of the object property OP2, that is if an individual x is

connected by OP1 to an individual y, then y is also connected by OP2

to x, and vice versa.

• InverseObjectProperties (a:hasFather a:fatherOf ) means that having

a father is the opposite of being a father of someone.


<owl:equivalentProperty>

<rdf:Description>

<owl:inverseOf rdf:resource="#fatherOf"/>

</rdf:Description>

</owl:equivalentProperty>


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Object Property Domain

rdfs:domain

• ObjectPropertyDomain (OP C): the domain of the object property

OP is the class C, that is, if an individual x is connected by OP with

some other individual, then x is an instance of C.

• ObjectPropertyDomain( a:hasDog a:Person ) means that only people

can own dogs.

<owl:ObjectProperty rdf:about="#hasDog">

<rdfs:domain rdf:resource="#Person"/>

…


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Object Property Range

rdfs:range

• ObjectPropertyRange(OP C): the range of the object property OP is

the class C , that is, if some individual is connected by OP with an

individual x, then x is an instance of C.

• ObjectPropertyRange( a:hasDog a:Dog ) means that the range of the

a:hasDog property is the class a:Dog.

<owl:ObjectProperty rdf:about="#hasDog">

…

<rdfs:range rdf:resource="#Dog"/>


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Functional Object Property

Owl:FunctionalProperty

• FunctionalObjectProperty (OP): the object property OP is functional,

that is, for each individual x, there can be at most one distinct

individual y such that x is connected by OP to y.

• Similar to the Uniqueness constraint in ORM.

• FunctionalObjectProperty (a:hasFather ) means that each object can

have at most one father.


<rdf:type rdf:resource="&owl;FunctionalProperty"/>

…


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Inverse-Functional Object Property

Owl:InverseFunctionalProperty

• InverseFunctionalObjectProperty (OPI ): the object property OPI is

inverse-functional, that is, for each individual x, there can be at most

one individual y such that y is connected by OP with x.

• InverseFunctionalObjectProperty (a:fatherOf ) means that each

object can have at most one father.

<owl:ObjectProperty rdf:about="#fatherOf">

<rdf:type rdf:resource="&owl;InverseFunctionalProperty"/>

…


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OWL2Example2

• In what follows we illustrate a simple example represented in ORM and OWL 2.

• In the example, the illustrated OWL 2 constructs are Object Subproperties, Inverse Object

Properties, Object Property Domain, Object Property Range and Functional Object

Properties.

...

<Class rdf:about="&OWL2Example2:Person"/>

<Class rdf:about="&OWL2Example2:Vehicle"/>

<Class rdf:about="&OWL2Example2:Gender"/>

<ObjectProperty rdf:about="&OWL2Example2:Drives">

<rdfs:domain rdf:resource="&OWL2Example2:Person"/>

<rdfs:range rdf:resource="&OWL2Example2:Vehicle"/>

</ObjectProperty>

<ObjectProperty rdf:about="&DrivenBy">

<inverseOf rdf:resource="OWL2Example2:Drives"/>

</ObjectProperty>

Has

Drives DrivenBy

VehiclePersonGender

Owns

<ObjectProperty rdf:about="&OWL2Example2:Owns">

<rdfs:domain rdf:resource="&OWL2Example2:Person"/>

<rdfs:range rdf:resource="&OWL2Example2:Vehicle"/>

</ObjectProperty>

<ObjectProperty rdf:about="&OWL2Example2:Owns">

<rdfs:subPropertyOf rdf:resource="&OWL2Example2:Drives"/>

</ObjectProperty>

<ObjectProperty rdf:about="&OWL2Example2:Has">

<rdf:type

rdf:resource="http://www.w3.org/2002/07/owl#FunctionalPropert

y"/>

</ObjectProperty>

…

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Assertions

• Class Assertions

• Individual Equality

• Individual Inequality

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Assertions

Class Assertions

owl:NamedIndividual

• ClassAssertion (C a ): the individual a is an instance of the class C.

• ClassAssertion (a:Person a:Mira ) means that Mira is a Person.

<owl:NamedIndividual rdf:about="#Mira">

<rdf:type rdf:resource="#Person"/>

</owl:NamedIndividual>

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Assertions

Individual Equality

owl:sameAs

• Identity between Individuals

• This mechanism is similar to that for classes, but declares two

individuals to be identical.

• SameIndividual ( a1 ... an ): all of the individuals ai, 1 ≤ i ≤ n, are equal

to each other(synonymes).

<Book rdf:ID=“http://www.amazon.com/Orientalism-Edward-W-Said/dp/039474067X">

<owl:sameAs rdf:resource=" http://en.wikipedia.org/wiki/Orientalism" />

</Book>

<rdf:Description rdf:about="#Edward_Said">

<owl:sameAs rdf:resource="# E_Said "/>

</rdf:Description>

<owl:Class rdf:ID="FootballTeam">

<owl:sameAs rdf:resource="http://sports.org/US#SoccerTeam"/>

</owl:Class>

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owl:differentFrom [OWL DL]

• An owl:differentFrom statement indicates that two URI references

refer to different individuals.

• It is needed where OWL 2 does not support unique name

assumption.

<Book rdf:ID="http://www.amazon.com/Orientalism-Edward-W-Said/dp/039474067X">

<owl:differentFrom

rdf:resource="http://www.youtube.com/watch?v=X3iA73JXIFo"/>

</Book>

Assertions

Individual Inequality

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Assertions

Individual Inequality (AllDifferent)

• The use of owl:differentFrom is likely to lead to a large number of

statements, as all individuals have to be declared pairwise disjoint.

• DifferentIndividuals( a1 ... an ): all of the individuals ai, 1 ≤ i ≤ n, are

different from each other; that is, no individuals ai and aj with i ≠ j can

be derived to be equal.

• DifferentIndividuals( a:Antoon a:Mustafa a:Rami ) Anton, Mustafa and

Rami are all different from each other.

<rdf:Description>

<rdf:type rdf:resource="&owl;AllDifferent"/>

<owl:distinctMembers rdf:parseType="Collection">

<rdf:Description rdf:about="#Anton"/>

<rdf:Description rdf:about="#Mustafa"/>

<rdf:Description rdf:about="#Rami"/>

</owl:distinctMembers>

</rdf:Description>

http://www.infowebml.ws/website/differentFrom.htm

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Class Expressions

• Intersection of Class Expressions

• Union of Class Expressions

• Complement of Class Expressions

• Enumeration of Individuals

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Class Expressions

Intersection of Class Expressions

owl:intersectionOf

Describes a class for which the class extension contains precisely those

individuals that are members of the class extension of all class

descriptions in the list. <owl:Class>

<owl:intersectionOf rdf:parseType="Collection">

<owl:Class>

<owl:oneOf rdf:parseType="Collection">

<owl:Thing rdf:about="#BirzeitUniversity" />

<owl:Thing rdf:about="#TeraCollage" />

</owl:oneOf>

</owl:Class>

<owl:Class>



<owl:Thing rdf:about="#AlqudsUniversity" />

<owl:Thing rdf:about="#AlnajahUniversity" />

</owl:oneOf>

</owl:Class>

</owl:intersectionOf>

</owl:Class>

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Class Expressions

Union of Class Expressions

owl:unionOf [OWL DL]

Describes an anonymous class for which the class extension contains

those individuals that occur in at least one of the class extensions of the

class descriptions in the list. <owl:Class>

<owl:unionOf rdf:parseType="Collection">

<owl:Class>



<owl:Thing rdf:about="#TeraCollage" />

</owl:oneOf>

</owl:Class>

<owl:Class>



<owl:Thing rdf:about="#AlqudsUniversity" />

<owl:Thing rdf:about="#AlnajahUniversity" />

</owl:oneOf>

</owl:Class>

</owl:unionOf>

</owl:Class>

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Class Expressions

Complement of Class Expressions

owl:complementOf [OWL DL]

• Describes a class for which the class extension contains exactly those

individuals that do not belong to the class extension of the class

description that is the object of the statement.

• Analogous to logical negation: the class extension consists of those

individuals that are NOT members of the class extension of the

complement class.<owl:Class rdf:ID="NotPalestinian">

<owl:intersectionOf rdf:parseType="Collection">

<owl:Class rdf:about="#Person"/>

<owl:Class>

<owl:complementOf>

<owl:Restriction>

<owl:onProperty rdf:resource="#hasParent" />

<owl:hasValue rdf:resource="#Palestine" />

</owl:Restriction>

</owl:complementOf>

</owl:Class>

</owl:intersectionOf>

</owl:Class>

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Class Expressions

Enumeration of Individuals

owl:one of [OWL DL]

• A list of individuals that are the instances of the class described.

• This enables a class to be described by exhaustively enumerating its

instances.

• The class extension of a class described with owl:oneOf contains

exactly the enumerated individuals, no more, no less.

<owl:Class>


<owl:Thing rdf:about="#Jerusalem "/>

<owl:Thing rdf:about="#Aka"/>

<owl:Thing rdf:about="#Gaza"/>

<owl:Thing rdf:about="#Nablus"/>

<owl:Thing rdf:about="#Hebron"/>

</owl:oneOf>

</owl:Class>

http://www.w3.org/TR/2004/REC-owl-ref-20040210/

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Class Expressions

Object Property Restrictions

• Existential Quantification

• Universal Quantification

• Individual Value Restriction

• Self-Restriction

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Class Expressions

Object Property Restrictions- Existential Quantification

owl:someValuesFrom

For all Accounts, they have at least one Owner that is a Peron.

<owl:Class rdf:ID=“Account">

<owl:Restriction>

<owl:onProperty rdf:resource="#HasOwner" />

<owl:someValuesFrom rdf:resource="#Person" />

</owl:Restriction>

</owl:Class>

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Class Expressions

Object Property Restrictions- Universal Quantification

owl:allValuesFrom

For all Accounts, if they have owners, all the owners are Persons.

<owl:Class rdf:ID=“Account">

<owl:Restriction>

<owl:onProperty rdf:resource="#HasOwner" />

<owl:allValuesFrom rdf:resource="#Person" />

</owl:Restriction>

</owl:Class>

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Class Expressions

Object Property Restrictions- Individual Value Restriction

owl:hasValue

ObjectHasValue( OP a ): consists of an object property OP and an

individual a, and it contains all those individuals that are connected

by OP to a.

…

<owl:Restriction>

<owl:onProperty rdf:resource="#fatherOf"/>

<owl:hasValue rdf:resource="#John"/>

</owl:Restriction>

…

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Class Expressions

Object Property Restrictions- Self Restriction

owl:hasSelf

• ObjectHasSelf( OP ): consists of an object property OP, and it

contains all those individuals that are connected by OP to themselves.

• ObjectHasSelf( a:hates ) contains those individuals that hate

themselves.

…

<owl:Restriction>

<owl:onProperty rdf:resource="#hates"/>

<owl:hasSelf rdf:datatype="&xsd;boolean">true</owl:hasSelf>

</owl:Restriction> …

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Class Expressions

Object Property Cardinality Restrictions

• Minimum Cardinality

• Maximum Cardinality

• Exact Cardinality

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Class ExpressionsObject Property Cardinality Restrictions- Minimum Cardinality

owl:Restriction , owl:onProperty, owl:minCardinality

• OWL allows us to place some restrictions on properties, such as

owl:minCardinality.

• The owl:Restriction below is to place a min cardinality constraint

on the property AuthorOf, at least one.

• This is similar to Mandatory in ORM

<owl:Class rdf:ID=“Book">

<rdfs:subClassOf>

<owl:Restriction>

<owl:onProperty rdf:resource="#AuthorOf"/>

<owl:minCardinality rdf:datatype="&xsd;nonNegativeInteger“>1</owl:minCardinality>

</owl:Restriction>

</rdfs:subClassOf>

...

</owl:Class>

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Class ExpressionsObject Property Cardinality Restrictions- Maximum Cardinality

owl:maxCardinality

• OWL allows us to place some restrictions on properties, such as

owl:maxCardinality.

• The owl:Restriction below is to place a max cardinality constraint on

the property AuthorOf, at most one.

• This is similar to unique in ORM.

<owl:Class rdf:ID=“Book">

<rdfs:subClassOf>

<owl:Restriction>

<owl:onProperty rdf:resource="#AuthorOf"/>

<owl:maxCardinality rdf:datatype="&xsd;nonNegativeInteger“>1</owl:maxCardinality>

</owl:Restriction>

</rdfs:subClassOf>

...

</owl:Class>

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Class ExpressionsObject Property Cardinality Restrictions - Cardinality

This permits the user to indicate 'at least one', 'no more than one', and

'exactly one'. For example: Each book has at least and at most (i.e.,

exactly) one ISBN value.

<owl:Class rdf:ID=“Book"> <rdfs:subClassOf>

<owl:Restriction> <owl:onProperty rdf:resource="#hasISBN"/>

<owl:cardinality rdf:datatype="&xsd;nonNegativeInteger">1</owl:cardinality> </owl:Restriction>

</rdfs:subClassOf> </owl:Class>

• Cardinality with values limited to 0 or 1 are part of OWL Lite.

• owl:maxCardinality can be used to specify an upper bound.

owl:minCardinality can be used to specify a lower bound.

• In combination, the two can be used to limit the property's cardinality to

a numeric interval.

• Positive integer values other than 0 and 1 are permitted in OWL DL.

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Class ExpressionsObject Property Cardinality Restrictions- Exact Cardinality

owl:qualifiedCardinality

The owl:Restriction below is to place an exact cardinality expression

that contains those individuals that are connected by a:hasVehicle to

exactly one instance of a:Car.

<owl:Class rdf:about="#Person">

<owl:equivalentClass>

<owl:Restriction>

<owl:onProperty rdf:resource="#hasVehicle"/>

<owl:onClass rdf:resource="#Car"/>

<owl:qualifiedCardinality

rdf:datatype="&xsd;nonNegativeInteger">1</owl:qualifiedCardinality>

</owl:Restriction>

</owl:equivalentClass>

</owl:Class>

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Property Chain Axioms

owl:propertyChainAxiom

Allows for inferring the existence of a property from a chain of

properties.

<rdf:Description rdf:about="hasGrandparent">

<owl:propertyChainAxiom rdf:parseType="Collection">

<owl:ObjectProperty rdf:about="hasParent"/>

<owl:ObjectProperty rdf:about="hasParent"/>

</owl:propertyChainAxiom>

</rdf:Description>

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XML Datatypes

xsd:string

xsd:normalizedString

xsd:boolean

xsd:decimal

xsd:float

xsd:double

xsd:integer

xsd:nonNegativeInteger

xsd:positiveInteger

xsd:nonPositiveInteger

xsd:negativeInteger

xsd:long

xsd:int

xsd:short

xsd:byte

xsd:unsignedLong

xsd:unsignedInt

xsd:unsignedShort

xsd:unsignedByte

xsd:hexBinary

xsd:base64Binary

xsd:dateTime

xsd:time

xsd:date

xsd:gYearMonth

xsd:gYear

xsd:gMonthDay

xsd:gDay

xsd:gMonth

xsd:anyURI

xsd:token

xsd:language

xsd:NMTOKEN

xsd:Name

xsd:NCName

The above datatypes, plus rdfs:Literal, form the built-in OWL datatypes.

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Properties of Individuals

We may also add properties between individuals.

<owl:ObjectProperty rdf:ID=“hasCapital"> .<rdfs:domain rdf:resource=“#Country" /> <rdfs:range rdf:resource="#City" />


<owl:ObjectProperty rdf:ID=“hasPopulation"> .<rdfs:domain rdf:resource=“#City" /> <rdfs:range rdf:resource=" xsd:integer />


<City rdf:ID=“Palestine"> <hasCapital rdf:resource="#J" />

</Region>

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References

• www.w3c.org

• www.w3schools.com

• Rami Hodrob, Mustafa Jarrar: ORM to OWL 2 DL

Mapping. In proceedings of the International Conference

on Intelligent Semantic Web – Applications and Services.

Pages 131-137. ACM ISBN 9781450304757. June 2010.

http://www.w3c.org/

http://www.w3c.org/

http://www.w3c.org/

http://www.w3schools.com/




http://www.jarrar.info/publications/




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