1. 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

2. Outline
Property Characteristics
OWL Restrictions

3. Knowledge Representation Part II, JPN, UiA
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).
Knowledge Representation Part II, JPN, UiA

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

5. Knowledge Representation Part III, JPN, UiA
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.
Knowledge Representation Part III, JPN, UiA

6. Functional Properties
A functional property connects only one object or literal to a subject.
birth mother: One's biological mother
E.g., it is only possible to have one birth mother
Knowledge Representation Part III, JPN, UiA

7. 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
Person
isBirthMotherTo *
birth mother: One's biological mother
0..1
Female
hasBirthMother
Knowledge Representation Part III, JPN, UiA

8. Inverse Functional Properties
If a property is inverse functional then it means that the inverse property is functional.
birth mother: One's biological mother
Knowledge Representation Part III, JPN, UiA

9. Functional / Inverse Functional Properties
Inverse functional properties are similar, but in the reverse direction.
Person
isBirthMotherTo
Inverse Functional Property *
birth mother: One's biological mother
Functional Property
0..1
Female
hasBirthMother
JPN, UiA

10. 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.
I seems this is why we need both???

11. 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

12. 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

13. 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

14. 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.
birth mother: One's biological mother
JPN, UiA

15. More Property Characteristics
parentOf
More Property Characteristics
Irreflexive, meaning that no individual can be related to itself by such a role. E.g., hasParent
birth mother: One's biological mother
Knowledge Representation Part III, JPN, UiA

16. Outline
Property Characteristics
OWL Restrictions

17. [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.

18. OWL Restrictions Three main categories: Quantifier Restrictions
existential restrictions
universal restrictions
Cardinality Restrictions
hasValue Restrictions

19. A restriction describes a class of individuals based on the relationships that members of the class participate in.
A restriction describes an anonymous class.

20. 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.

21. New version of Protégé calls it “Subclass of”

22. Existential Restrictions
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.

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

24. In Turtle Representation
pizza:Pizza rdf:type owl:Class ; rdfs:label ; rdfs:subClassOf [ rdf:type owl:Restriction ; owl:onProperty pizza:hasBase ; owl:someValuesFrom pizza:PizzaBase ] ; …
At least one pizza base!

26. pizza:Margherita rdf:type owl:Class ; rdfs:label ; rdfs:subClassOf pizza:NamedPizza , [ rdf:type owl:Restriction ; owl:onProperty pizza:hasTopping ; owl:allValuesFrom [ rdf:type owl:Class ; owl:unionOf ( pizza:MozzarellaTopping pizza:TomatoTopping ) ] ] , …
Only = owl:allValuesFrom

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

29. Multiple Inheritance from 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
] .

30. References
[1] Book: David Poole and Alan Mackworth, Artificial Intelligence: Foundations of Computational Agents, Cambridge University Press, 2010, [2] [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]