13 dec. 2006cmpe 583 fall 2006 owl lite- property char’s. 1 owl lite: ch. 13- property...

13 Dec. 2006 CmpE 583 Fall 2006 OWL Lite- Property Char’s. 1

OWL Lite: Ch. 13- Property Characteristics

Atilla ELÇİ


Property Characteristics

• To provide additional detail info on properties beyond their declaration

• Metaproperties (properties of properties) and classes for general statements about properties:– Global property restrictions– Relating properties– Inference shortcuts– Local property restrictions


Global Property Restrictions

• In order to restrict all uses of a property

• These are:– Those provided by RDFS:

• rdfs:domain• rdfs:range.

– Functional property– Inverse functional property

13 Dec. 2006Rev. 29/12/08

CmpE 583 Fall 2006 OWL Lite- Property Char’s. 4

Global Property Restrictions (continued)

• Functional Property (owl:FunctionalProperty):– A functional property can have at most a unique value for a

particular subject individual, that is, no value or one value only. <owl:ObjectProperty rdf:ID=“hasPrice”>

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

That is, a particular item may not have a price (if the property has not been stated for it) or can have only one value for hasPrice property.

– Implications:• If a reasoner finds a value for a functional property of a subject, it

stops looking for more!• If a validating software (such as Prolog program testing a case

question) finds more than one value, that indicates that the assertion has created an illegal condition. => Assertions are not valid!

• If an individual has two items (different URIRefs) for value for a functional property, then these items are the same.


Global Property Restrictions (continued)

• Inverse Functional Property (owl:InverseFunctionalProperty):– Opposite relationship of a functional property is an inverse functional

property. – Identifies object properties whose values uniquely identify the subject

instance of a property.<owl:ObjectProperty rdf:ID=“hasIDNumber”>

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

In typed node syntax:<owl:InverseFunctionalProperty rdf:ID=“hasIDNumber” /> That is, a value of hasIDNumber relation identifies one particular (a unique)

subject.– Implications:

• If a reasoner finds two URIrefs that identify resources with the same value for an OWL inverse functional property, it means that the two are referencing the same resource.

• Inverse of an inverse functional property is functional!

13 Dec. 2006Rev. 23/12/08


Relating Properties

• Property equivalence (owl:equivalentProperty):– Equivalent properties relate the same subject resource to the

same value (object resource) where both are properties). Ex.: <owl:ObjectProperty rdf:ID=“menuPrice”>

<owl:equivalentProperty rdf:resource=“#menuCost”/></owl:ObjectProperty>

where menuPrice & menuCost are equivalenced.– Subclass of owl:sameAs & rdfs:subPropertyOf property.– Good for “merging” ontologies by combining their symbol tables

without actually combining the ontology documents.– Applies on any rdf:Property and returns an rdf:Property instance.


Relating Properties (continued)

• Inverse Property (owl:inverseOf Property):– An inverse property relates a value (in the range) of a property back to its domain: just like

the derefencing in C/C++. Ex.:<owl:ObjectProperty rdf:ID=“usedInDish”>

<rdfs:comment>Means that the ingredient having this property is used in a dish</rdfs:comment></owl:ObjectProperty><owl:ObjectProperty rdf:ID=“hasIngredients”>

<rdfs:comment>Means that the dish having this property uses an ingrediant</rdfs:comment><owl:inverseOf rdf:resource=“#usedInDish”/>

</owl:ObjectProperty><Ingredient rdf:ID=“sugar”><rdfs:label>Refined Sugar</rdfs:label></Ingredient><MenuItem rdf:ID=“baklava”>

<rdfs:label>Turkish Baklava</rdfs:label><hasIngredient rdf:resource=“#sugar”/>

</MenuItem>– A reasoner than infers that:<Ingredient rdf:about=“#sugar”>

<usedInDish rdf:resource=“#baklava”7></Ingredient>– Note that inverseOf is symmetric! – Applies on any owl:ObjectProperty and returns an owl:ObjectProperty instance.


Inference Shortcuts• OWL statements in aid of inference engines: membership in

predefined Transitive/Symmetric Object Property classes.• Transitive Property (owl:TransitiveProperty):

– Means same as in math: A<B<C => A<C.<owl:TransitiveProperty rdf:ID=“smallerThan”/><rest:Restaurant rdf:ID=“compKanteen”>

<rdf:smallerThan rdf:resource=“#pizzaPizza”/></rest:Restaurant><rest:Restaurant rdf:ID=“pizzaPizza”>

<rdf:smallerThan rdf:resource=“#central”/></rest:Restaurant>This example implies that compKanteen < central.– NB: there are several restrictions on the use of transitive property in

OWL Lite: • no local/global cardinality contraint on themselves, their inverses, or their

superproperties;• No functional/inverse functional designation;• Domain & range must match in use (see ex above);• Applies only on owl:ObjectProperty instances.

13 Dec. 2006Rev. 30/12/08


Inference Shortcuts (continued)

• Symmetric Property (owl:SymmetricProperty):– A symmetric property also relates values back to subject resources, that

is, it implies a relationship in the opposite direction.<owl:SymmetricProperty rdf:ID=“goesWellWith”/><MenuItem rdf:ID=“kadayif”>

<rdfs:label>Tel Kadayif</rdfs:label></MenuItem><MenuItem rdf:ID=“cream”>

<rdfs:label>Turkish Kaymak</rdfs:label><goesWellWith rdf:resource=“#kadayif”/>

</MenuItem>– A reasoner than infers that :kadayif :goesWellWith :cream .– NB: there are restrictions on the use of symmetric property in OWL Lite:

• If the domain and range of a symmetric property are restricted, they must be the same.


Local Property Restrictions

• owlRestriction:– Used to apply a property restriction to a

particular class extension rather than all classes.

– Can be of:• owl:onProperty• Value restriction• Cardinality restriction

13 Dec. 2006Rev. 29/12/08


Local Property Restrictions (continued)

• owlRestriction / owl:onProperty:– onProperty property identifies the object property or

datatype property being restricted. Another property is used to mark the specific kind of restriction.

<owl:Restriction><owl:onProperty rdf:resource= “<propertyName>”>< ... Specifics of the restriction ... />

</owl:Restriction>– The two types of local restrictions are:

• Property value restriction• Property cardinality restriction.

13 Dec. 2006Rev. 29/12/08



• Value contraints:– Used to further and individually restrict the range of a property.– The Universal quantifier: owl:allValuesFrom:<owl/Restriction>

<owl:onProperty rdf:resource= “#dishFeeds”><owl:allValuesFrom rdf:resource=“&xsd;nonNegativeInteger”/>

</owl:Restriction>• The universal quantifier takes a class expression or datatype.

– The Existential Quantifier: owl:someValuesFrom:• At least one value of the restricted property must be an instance of

the specified class.<owl/Restriction>

<owl:onProperty rdf:resource= “#sideOrder”><owl:someValuesFrom rdf:resource=“#Salads”/>

</owl:Restriction>

13 Dec. 2006Rev. 29/12/08



Cardinality contraints:

Used to restrict the number of values a property should have for subject members from a particular subject description.

• The value of a cardinality constraint is restricted to 0 or 1 in OWL Lite meaning that:

– 0: to prohibit the use of a property or limit the number of occurrences.– 1: to require a property or limit the number of occurrences.

• Minimum cardinality (owl:minCardinality):– Example: in stating an optional item:

<owl/Restriction><owl:onProperty rdf:resource=“#hasCar”><owl:minCardinality rdf:datatype=“&xsd;nonNegativeInteger>0</owl:minCardinality>

</owl:Restriction>– Example: in stating absolute requirement of an item:

<owl/Restriction><owl:onProperty rdf:resource=“#hasTextBook”><owl:minCardinality rdf:datatype=“&xsd;nonNegativeInteger>1</owl:minCardinality>

</owl:Restriction>

13 Dec. 2006Rev. 29/12/08



Cardinality contraints (continued) :

• Maximum cardinality (owl:maxCardinality):– Example: in stating an absolute maximum of values for a class’s

property:<owl/Restriction>

<owl:onProperty rdf:resource= “#hasProjectPartner”><owl:maxCardinality rdf:datatype=“&xsd;nonNegativeInteger>0</owl:maxCardinality>

</owl:Restriction>• Absolute cardinality (owl:Cardinality):

– May be used as shorthand for min/max cardinality. In OWL Lite only 0/1 is allowed.

• For a summary of various cardinality features and purpose of use, please refer to Table 13-5 Using Appropriate Cardinality Statements and Values and Table 16.2 OWL Lite Restriction Summary

13 dec. 2006cmpe 583 fall 2006 owl lite- property char’s. 1 owl lite: ch. 13- property...

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