Knowledge Representation Part VII Protg / RDFS / OWL / ++ Much of - PowerPoint PPT Presentation

Knowledge Representation Part VII Protégé / RDFS / OWL / ++ Much of the content of this presentation has been copied from: A Practical Guide To Building OWL Ontologies Using Protégé 4 and CO-ODE Tools Edition 1.3, Matthew Horridge Jan Pettersen Nytun, UiA 1

S O P Outline • Property Characteristics • OWL Restrictions Jan Pettersen Nytun, UiA, Ontologies, page 2

S OWL O P Property types • There are two main types of properties: – Object properties. – Datatype properties. • Additionally: Annotation properties can be used to add metadata (data about data). Knowledge Representation Part II, JPN, UiA 3

S O P Property Characteristics OWL allows the meaning of properties to be enriched through the use of property characteristics. Knowledge Representation Part III, JPN, UiA 4

S Inverse Property O P • If some property links individual A to individual B then its inverse property will link individual B to individual A . • If Matthew hasParent Jean, then because of the inverse property we can infer that Jean hasChild Matthew. Knowledge Representation Part III, JPN, UiA 5

S Functional Properties O P • A functional property connects only one object or literal to a subject. E.g., it is only possible to have one birth mother Knowledge Representation Part III, JPN, UiA 6

S Functional Properties Continues … O P Mapping functional property to UML: It is possible to define an association as functional by specifying the upper multiplicity of the navigable end as being 0..1 isBirthMotherTo Person * 0..1 Female hasBirthMother Knowledge Representation Part III, JPN, UiA 7

S O P Inverse Functional Properties • If a property is inverse functional then it means that the inverse property is functional. Knowledge Representation Part III, JPN, UiA 8

S Functional / Inverse Functional Properties O P Inverse functional properties are similar, but in the reverse direction. isBirthMotherTo Person * Inverse Functional Property Functional Property 0..1 Female hasBirthMother JPN, UiA 9

S O P Functional / Inverse Functional Properties continues … • Both object properties and datatype properties can be declared as " functional“ but only object properties can be decleared to be “functional inverse”. • RDF does not allow literal values as the subjects of triples. 10

S O P More Property Characteristics If a property is transitive , and the property relates individual a to individual b, and also individual b to individual c, then we can infer that individual a is related to individual c via property P. E.g., subRegionOf JPN, UiA 11

S O P More Property Characteristics If a property P is symmetric , and the property relates individual a to individual b then individual b is also related to individual a via property P. E.g., hasSibling JPN, UiA 12

S O P More Property Characteristics If a property P is asymmetric , and the property relates individual a to individual b then individual b cannot be related to individual a via property P. E.g., isMotherTo JPN, UiA 13

S O P More Property Characteristics A property P is said to be reflexive when the property must relate individual to itself. E.g., hasRelative ( everybody has himself as a relative). This does not necessarily mean that every two individuals which are related by a reflexive property are identical. JPN, UiA 14

S parentOf O P More Property Characteristics Irreflexive , meaning that no individual can be related to itself by such a role. E.g., hasParent Knowledge Representation Part III, JPN, UiA 15

S O P Outline • Property Characteristics • OWL Restrictions Jan Pettersen Nytun, UiA, Ontologies, page 16

S O P [4]: In OWL classes are built up of descriptions that specify the conditions that must be satisfied by an individual for it to be a member of the class. Jan Pettersen Nytun, UiA, page 17

S O P OWL Restrictions • Three main categories: – Quantifier Restrictions • existential restrictions • universal restrictions – Cardinality Restrictions – hasValue Restrictions Jan Pettersen Nytun, UiA, Ontologies, page 18

S O P • A restriction describes a class of individuals based on the relationships that members of the class participate in. • A restriction describes an anonymous class. Jan Pettersen Nytun, UiA, Ontologies, page 19

S O P Quantifier Restrictions – Existential restrictions – some Describe classes of individuals that participate in at least one relationship along a specified property to individuals that are members of a specified class. – Universal restrictions – only Describe classes of individuals that for a given property only have relationships along this property to individuals that are members of a specified class. Jan Pettersen Nytun, UiA, Ontologies, page 20

S New version of Protégé O P calls it “Subclass of”

S Existential Restrictions O P A restriction containing an owl:someValuesFrom constraint describes a class of all individuals for which at least one value of the property concerned is an instance of the class description or a data value in the data range. Jan Pettersen Nytun, UiA, Ontologies, page 22

S O P Cardinality in dialog window should be ignored (it is 1..*) Jan Pettersen Nytun, UiA, Ontologies, page 23

In Turtle Representation S O P pizza:Pizza rdf:type owl:Class ; rdfs:label "Pizza"@en ; At least one pizza base! rdfs:subClassOf [ rdf:type owl:Restriction ; owl:onProperty pizza:hasBase ; owl:someValuesFrom pizza:PizzaBase ] ; … Jan Pettersen Nytun, UiA, page 24

S O P Jan Pettersen Nytun, UiA, Ontologies, page 25

P pizza:Margherita rdf:type owl:Class ; S O Only = owl:allValuesFrom rdfs:label "Margherita"@pt ; rdfs:subClassOf pizza:NamedPizza , [ rdf:type owl:Restriction ; owl:onProperty pizza:hasTopping ; owl:allValuesFrom [ rdf:type owl:Class ; owl:unionOf ( pizza:MozzarellaTopping pizza:TomatoTopping ) ] ] , …

S O P Jan Pettersen Nytun, UiA, Ontologies, page 27

S O P There is no “+” for adding; conditions comes from superclass! Jan Pettersen Nytun, UiA, Ontologies, page 28

S Multiple Inheritance from O P Anonymous Classes :Pizza rdf:type owl:Class ; rdfs:subClassOf [ rdf:type owl:Restriction ; owl:onProperty :hasTopping ; owl:someValuesFrom :PizzaTopping ] , [ rdf:type owl:Restriction ; owl:onProperty :hasBase ; owl:someValuesFrom :PizzaBase ] . Jan Pettersen Nytun, UiA, Ontologies, page 29

S References O P [1] Book: David Poole and Alan Mackworth, Artificial Intelligence: Foundations of Computational Agents , Cambridge University Press, 2010, http://artint.info/ [2] http://www.w3.org/TR/swbp-n-aryRelations/ [3] RDF 1.1 Primer, W3C Working Group Note, 24 June 2014 [4] A Practical Guide To Building OWL Ontologies Using Protégé 4 and CO-ODE Tools Edition 1.3, Matthew Horridge [5] http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/ Jan Pettersen Nytun, UiA, Propositional Calculus, page 30