1. Semantic Web for the Working Ontologist Dean Allemang Jim Hendler SNU IDB laboratory

2. Semantic Web for the Working OntologistDean Allemang, Jim Hendler Working Ontology Contents 2 ■ Chapter 1 What is the Semantic Web? ■ Chapter 2 Semantic Modeling ■ Chapter 3 RDF-The Basis of the semantic Web ■ Chapter 4 Semantic Web Application Architecture ■ Chapter 5 RDF and Inferencing ■ Chapter 6 RDF Schema ■ Chapter 7 RDFS-Plus ■ Chapter 8 Using RDFS-Plus in the Wild ■ Chapter 9 Basic OWL ■ Chapter 10 Counting and Sets in OWL ■ Chapter 11 Using OWL in the Wild ■ Chapter 12 Good and Bad Modeling Practices ■ Chapter 13 OWL Levels and Logic

3. Semantic Web for the Working OntologistDean Allemang, Jim Hendler Chapter 9 Basic OWL ■ 1. Restrictions ■ 2. Challenge Problems ■ 3. Relationship Transfer in FOAF ■ 4. Alternative Descriptions of Restrictions 3

4. Semantic Web for the Working OntologistDean Allemang, Jim Hendler Introduction 4 RDFS-Plus < OWL OWL provides a systematic treatment of information description & constructs for describing information structure

5. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 1. Restrictions ■ owl:Restriction We can describe new classes in terms of classes that have already been defined Example 5 BaseballTeam MajorLeagueTeamBaseballPlayer subClassOfPlaysFor MajorLeaguePlayer Someone who plays on a MajorLeagueTeam Restriction Membership in the class MajorLeaguePlayer is restricted to those things that play for a MajorLeagueTeam

6. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 1. Restriction - Adding “Restrictions” ■ owl:Restriction A class that is defined by a description of its members in terms of existing properties and classes Providing some description that limits the kinds of things that can be said about a member of this class 6 SUBJECT OBJECT OrbitsAround Anything orbits-Around anything else If we restrict the value of orbitsAround by saying that its object must be TheSun The SUN → All things orbit around the sun!

7. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 1. Restriction - Kinds of Restrictions ■ A restriction class in OWL is defined by the keyword owl:onProperty owl:onProperty orbitsAround owl:onProperty playsFor ■ owl:allValuesFrom ■ owl:someValuesFrom ■ owl:hasValue 7

8. Semantic Web for the Working OntologistDean Allemang, Jim Hendler ■ owl:someValueFrom All individuals for which at least one value of the property P comes from class C Example : The class AllStarPlayer ▶ All individuals for which at least one value of the property playsFor comes from the class AllStarTeam 8 1. Restriction - Kinds of Restrictions : owl:someValuesFrom AllStarPlayer [ a owl:Restriction; owl:onProperty :playsFor; owl:someValuesFrom :AllStarTeam] Object PlaysFor [ a owl:Restriction; owl:onProperty P; owl:someValuesFrom C]

9. Semantic Web for the Working OntologistDean Allemang, Jim Hendler ■ owl:allValueFrom The individuals for which all values of the property P come from class C Example 9 1. Restriction - Kinds of Restrictions : owl:allValuesFrom [ a owl:Restriction; owl:onProperty P; owl:allValuesFrom C] MyFavoriteAllStarTeam → Every player on MyFavoriteAllStarTeam is a StarPlayer MyFavoriteAllStarTeam hasPlayer Kaneda MyFavoriteAllStarTeam hasPlayer Gonzales BOTH Kaneda and Gonzales must be of type StarPlayer Object hasPlayer [ a owl:Restriction; owl:onProperty hasPlayer owl:allValuesFrom StarPlayer]

10. Semantic Web for the Working OntologistDean Allemang, Jim Hendler ■ owl:someValueFrom VS owl:allValueFrom owl:someValueFrom ▶ Restriction: there is at least one member of a class with a particular property ▶ There MUST be such a MEMBER owl:allValueFrom ▶ If there are any members, then they all must have this property ▶ This does NOT imply that there are any members 10 1. Restriction - Kinds of Restrictions : owl:allValuesFrom

11. Semantic Web for the Working OntologistDean Allemang, Jim Hendler ■ owl:hasValueFrom The individuals that have the value A for the property P The hasValue restriction is just a special case of the someValuesFrom restriction, →in which the class C happens to be a singleton set {A} 11 1. Restriction - Kinds of Restrictions : owl:hasValuesFrom [ a owl:Restriction; owl:onProperty P; owl:hasValue A] [ a owl:Restriction; owl:onProperty P; owl:someValuesFrom C]

12. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Local Restriction of Ranges ■ Example : Describing a vegetarian diet 12 & :Person a owl:Class. :Food a owl:Class. :eats rdfs:domain :Person. :eats rdfs:range :Food. :Maverick :eat :Steak. :Maverick a :Person. :Steak a :Food.

13. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Local Restriction of Ranges ■ Example : We want to define a variety of diets in more detail 13 & :Vegetarian a owl:Class; rdfs:subClassOf :Person. :VegetarianFood a owl:Class; rdfs:subClassOf :Food. :Jen a :Vegetarian ; :eats :Marzipan. :Marzipan a :VegetarianFood. ?

14. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Local Restriction of Ranges ■ Example : How can the relationship between vegetarians and vegetarian food be correctly modeled with the use of the owl:Restriction? ■ Solution : We can define the set of things that only eat VegetarianFood using a RESTRICTION 14 :eats rdfs:domain :Vegetarian. :eats rdfs:range :VegetarianFood. :Maverick a :Vegetarian. :Steak a :VegetarianFood. NO! :Vegetarian rdfs:subClassOf [ a owl:Restriction; owl:onProperty :eats ; owl:allValuesFrom :VegetarianFood]. :Jen a :vegetarian. :Jen a [a owl:Restriction; owl:onProperty :eats ; owl:allValuesFrom :VegetarianFood]. :Jen eats :Marzipan.:Marzipan a :VegetarianFood.

15. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Filtering Data Based on Explicit Type ■ Example: Build a model in OWL based on the value in the “Product Line” ■ Solution Define the classes 15 ns:Paper_Machinerdf:typeowl:Class. ns:Feedback_Linerdf:typeowl:Class. ns:Active_Sensorrdf:typeowl:Class. ns:Monitor rdf:typeowl:Class. ns:Safety_Valverdf:typeowl:Class.

16. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Filtering Data Based on Explicit Type Each of these classes must include just those individuals with the appropriate value for the property mfg:Product_Product_Line → owl:hasValue 16 ns:Paper_Machineowl:equivalentClass [a owl:Restriction; owl:onProperty mfg:Product_Product_Line owl:hasValue “Paper machine”]. ns:Feedback_Lineowl:equivalentClass [a owl:Restriction; owl:onProperty mfg:Product_Product_Line owl:hasValue “Feedback Line”]. ns:Active_Sensorowl:equivalentClass [a owl:Restriction; owl:onProperty mfg:Product_Product_Line owl:hasValue “Active Sensor”]. ns:Monitor owl:equivalentClass [a owl:Restriction; owl:onProperty mfg:Product_Product_Line owl:hasValue “Monitor”]. ns:Safety_Valveowl:equivalentClass [a owl:Restriction; owl:onProperty mfg:Product_Product_Line owl:hasValue “Safety_Valve”].

17. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Filtering Data Based on Explicit Type Inference: Consider mfg:Product1 (“ZX-3”) 17 mfg:Product1 mfg:Product_Product_Line “Paper machine” mfg:Product1 rdf:type [ a owl:Restriction; owl:onProperty mfg:Product_product_Line owl:hasValue “Paper machine”]. mfg:Product1 rdf:type mfg:Paper_Machine

18. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Filtering Data Based on Explicit Type This definition maintains coherence of the data, even if it came from a source other than the imported table 18 os:ProductA rdf:type mfg:Paper_Machine os:ProductA rdf:type [ a owl:Restriction; owl:onProperty mfg:Product_product_Line owl:hasValue “Paper machine”]. os:ProductA mfg:Product_Product_Line “Peper Machine” Owl:equivalnetClass

19. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Filtering Data Based on Explicit Type The end result of this construct is that regardless of how product information is brought into the system, it is represented both in terms of rdf:type and mfg:Product_Product_Line consistently 19

20. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Relationship Transfer in SKOS ■ Everything related to A by property p should also be related to B but by property q Relationship transfer : Transferring individuals in a relationship with one entity to another relationship with another entity 20 All Star Team League’s contract Collected works of Shakespeare Written by Shakespeare

21. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 2. Challenge Problems - Challenge: Relationship Transfer in SKOS ■ SKOS (Chapter 8) Relationship transfer appears in this system ▶ skos:narrower in the context of a skos:Collection is a relationship transfer 21 X skos:narrower C. C skos:member Y. X skos:narrower Y.

22. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 3. Relationship Transfer in FOAF ■ Example: The life of Shakespeare FOAF specifies that the following rule should hold: 22 b:Shakespeare_Children a foaf:Group ; foaf:name “Shakespeare’s Children”; foaf:member b:Susanna, b:Judith, b:Hamnnet; foaf:membershipClass b:ChildOfShakespeare. b:ChildOfShakespeare a owl:Class. IF b:Shakespeares_Children foaf:member ?x THEN ?x rdfs:type b:ChildOfShakespeare.

23. Semantic Web for the Working OntologistDean Allemang, Jim Hendler 4. Alternative Descriptions of Restrictions ■ The semantic of rdfs:subClassOf and owl:equivalentClass rdfs:subClassOf ▶ IF/THEN relation ; If something is a member of X, then it is also a member of Y owl:equivalentClass ▶ IF and only IF relation ; If something is a member of X, then it is also a member of Y, and vice versa These relations remain unchanged in the case where X and/or Y are restrictions 23 X rdfs:subClassOf Y. X owl:equivalentClass Y.

24. Semantic Web for the Working OntologistDean Allemang, Jim Hendler ■ Example If something is a solar body, then it orbits the sun ▶ Orbiting the sun is a necessary condition for SolarBody ▶ Orbiting the sun is a partial definition for the class SolarBody Solar bodies are the same as the set of things that orbit the sun ▶ Orbiting the sun is a necessary and sufficient condition for SolarBody ▶ Orbiting the sun is a complete definition for the class SolarBody All thing that orbit the sun are solar bodies 24 4. Alternative Descriptions of Restrictions A rdfs:subClassOf B. SolarBody Unnamed class defined by a restriction onProperty orbits that it hasValue TheSun A owl:equivalnetClass B. B rdf:subClassOf A. HOWEVER, These are no common practice to use the word such as partial, complete, sufficient, and necessary … → rdfs:subClassOf & owl:equivalentClass