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

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

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


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Knowledge Representation Part VII Protégé / RDFS / OWL / ++

Jan Pettersen Nytun, UiA 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

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Outline

  • Property Characteristics
  • OWL Restrictions

Jan Pettersen Nytun, UiA, Ontologies, page 2

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OWL 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).

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Property Characteristics

OWL allows the meaning of properties to be enriched through the use of property characteristics.

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Inverse Property

  • 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.

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Functional Properties

  • A functional property connects only one object or

literal to a subject.

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E.g., it is only possible to have one birth mother

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Functional Properties Continues …

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

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Person Female

hasBirthMother isBirthMotherTo 0..1 *

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Inverse Functional Properties

  • If a property is inverse functional then it means

that the inverse property is functional.

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Functional / Inverse Functional Properties

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Person Female

hasBirthMother isBirthMotherTo 0..1 *

Inverse Functional Property Functional Property

Inverse functional properties are similar, but in the reverse direction.

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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.

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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

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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

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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

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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.

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More Property Characteristics

Irreflexive, meaning that no individual can be related to itself by such a role. E.g., hasParent

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parentOf

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Outline

  • Property Characteristics
  • OWL Restrictions

Jan Pettersen Nytun, UiA, Ontologies, page 16

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[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

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OWL Restrictions

  • Three main categories:

– Quantifier Restrictions

  • existential restrictions
  • universal restrictions

– Cardinality Restrictions – hasValue Restrictions

Jan Pettersen Nytun, UiA, Ontologies, page 18

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  • 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

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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

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New version of Protégé calls it “Subclass of”

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Existential Restrictions

Jan Pettersen Nytun, UiA, Ontologies, page 22

A restriction containing an

  • wl: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.

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Jan Pettersen Nytun, UiA, Ontologies, page 23

Cardinality in dialog window should be ignored (it is 1..*)

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In Turtle Representation

pizza:Pizza rdf:type owl:Class ; rdfs:label "Pizza"@en ; rdfs:subClassOf [ rdf:type owl:Restriction ;

  • wl:onProperty pizza:hasBase ;
  • wl:someValuesFrom pizza:PizzaBase

] ; …

Jan Pettersen Nytun, UiA, page 24

At least one pizza base!

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Jan Pettersen Nytun, UiA, Ontologies, page 25

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Ppizza:Margherita rdf:type owl:Class ;

rdfs:label "Margherita"@pt ; rdfs:subClassOf pizza:NamedPizza , [ rdf:type owl:Restriction ;

  • wl:onProperty pizza:hasTopping ;
  • wl:allValuesFrom [ rdf:type owl:Class ;
  • wl:unionOf ( pizza:MozzarellaTopping

pizza:TomatoTopping ) ] ] , … Only = owl:allValuesFrom

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Jan Pettersen Nytun, UiA, Ontologies, page 27

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Jan Pettersen Nytun, UiA, Ontologies, page 28

There is no “+” for adding; conditions comes from superclass!

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Multiple Inheritance from Anonymous Classes

Jan Pettersen Nytun, UiA, Ontologies, page 29

:Pizza rdf:type owl:Class ; rdfs:subClassOf [ rdf:type owl:Restriction ;

  • wl:onProperty :hasTopping ;
  • wl:someValuesFrom :PizzaTopping

] , [ rdf:type owl:Restriction ;

  • wl:onProperty :hasBase ;
  • wl:someValuesFrom :PizzaBase

] .

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References

Jan Pettersen Nytun, UiA, Propositional Calculus, page 30

[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/