1 Berendt: Knowledge and the Web, 1st semester 2014/2015, 1 Knowledge and the Web Inference on the Semantic Web Bettina Berendt KU Leuven, Department of Computer Science Last update: October 15, 2014

2 Berendt: Knowledge and the Web, 1st semester 2014/2015, 2 Agenda OWL: Protégé interface, XML/RDF OWL viewed as a description logics: basics OWL: another syntax (for the examples that follow) OWL inference examples Common problems in using OWL reasoning

3 Berendt: Knowledge and the Web, 1st semester 2014/2015, 3 Agenda OWL: Protégé interface, XML/RDF OWL viewed as a description logics: basics OWL: another syntax (for the examples that follow) OWL inference examples Common problems in using OWL reasoning

4 Berendt: Knowledge and the Web, 1st semester 2014/2015, 4 Motivation; deductive and inductive reasoning (ex.s) n Deductive reasoning l All swans are white. l Tilly is a swan.  Tilly is white. l Truth-preserving! n Inductive reasoning l Tilly and Edda and Edwin and … are swans. l Tilly and Edda and Edwin and … are white.  All swans are white. l „Bringing new knowledge into the world“

5 Berendt: Knowledge and the Web, 1st semester 2014/2015, 5 (OWL slides)

6 Berendt: Knowledge and the Web, 1st semester 2014/2015, 6 Agenda OWL: Protégé interface, XML/RDF OWL viewed as a description logics: basics OWL: another syntax (for the examples that follow) OWL inference examples Common problems in using OWL reasoning

7 Berendt: Knowledge and the Web, 1st semester 2014/2015, 7 OWL Abstract Syntax / OWL Functional Syntax (ex. 1) Class(bus partial vehicle) XML/RDF Functional syntax Pro- tégé

8 Berendt: Knowledge and the Web, 1st semester 2014/2015, 8 OWL Abstract Syntax / OWL Functional Syntax (ex. 2) (in the Protégé editor: “Person and drives some Bus“ ) Class(bus_driver complete intersectionOf( person restriction(drives someValuesFrom (bus))))

9 Berendt: Knowledge and the Web, 1st semester 2014/2015, 9 Agenda OWL: Protégé interface, XML/RDF OWL viewed as a description logics: basics OWL: another syntax (for the examples that follow) OWL inference examples Common problems in using OWL reasoning

10 Berendt: Knowledge and the Web, 1st semester 2014/2015, 10 Examples: Class inferences (1) Class(a:bus_driver complete intersectionOf( a:person restriction(a:drives someValuesFrom (a:bus)))) Class(a:driver complete intersectionOf( a:person restriction(a:drives someValuesFrom(a:vehicle)))) Class(a:bus partial a:vehicle) Note: a is the namespace used throughout these examples

11 Berendt: Knowledge and the Web, 1st semester 2014/2015, 11 Examples: Class inferences (2) Class(a:cat_owner complete intersectionOf( a:person restriction(a:has_pet someValuesFrom (a:cat)))) SubPropertyOf(a:has_pet a:likes) Class(a:cat_liker complete intersectionOf( a:person restriction(a:likes someValuesFrom (a:cat))))

12 Berendt: Knowledge and the Web, 1st semester 2014/2015, 12 Examples: Class inferences (3) Class(a:driver complete intersectionOf( a:person restriction(a:drives someValuesFrom(a:vehicle)))) Class(a:driver partial a:adult) Class(a:grownup complete intersectionOf( a:adult a:person))

13 Berendt: Knowledge and the Web, 1st semester 2014/2015, 13 Examples: Class inferences (4) Class(a:sheep partial a:animal restriction(a:eats allValuesFrom (a:grass))) Class(a:grass partial a:plant) DisjointClasses( unionOf(a:animal restriction(a:part_of someValuesFrom (a:animal))) unionOf(a:plant restriction(a:part_of someValuesFrom (a:plant)))) Class(a:vegetarian complete intersectionOf( a:animal restriction(a:eats allValuesFrom (complementOf(a:animal))))) restriction(a:eats allValuesFrom (complementOf(restriction(a:part_of someValuesFrom (a:animal))))) This was missing on your printouts

14 Berendt: Knowledge and the Web, 1st semester 2014/2015, 14 Examples: Class inferences (5) Class(a:giraffe partial a:animal restriction(a:eats allValuesFrom (a:leaf))) Class(a:leaf partial restriction(a:part_of someValuesFrom (a:tree))) Class(a:tree partial a:plant) DisjointClasses( unionOf(restriction(a:part_of someValuesFrom (a:animal)) a:animal) unionOf(a:plant restriction(a:part_of someValuesFrom (a:plant)))) Class(a:vegetarian complete intersectionOf( a:animal restriction(a:eats allValuesFrom (complementOf(restriction(a:part_of someValuesFrom (a:animal))))) restriction(a:eats allValuesFrom (complementOf(a:animal)))))

15 Berendt: Knowledge and the Web, 1st semester 2014/2015, 15 Examples: Class inferences (6) Class(a:old_lady complete intersectionOf(a:person a:female a:elderly)) Class(a:old_lady partial intersectionOf( restriction(a:has_pet someValuesFrom (a:animal)) restriction(a:has_pet allValuesFrom (a:cat)))) Class(a:cat_owner complete intersectionOf( a:person restriction(a:has_pet someValuesFrom (a:cat))))

16 Berendt: Knowledge and the Web, 1st semester 2014/2015, 16 Examples: Class inferences (7) Class(a:cow partial a:vegetarian) DisjointClasses( unionOf(a:animal restriction(a:part_of someValuesFrom (a:animal))) unionOf(a:plant restriction(a:part_of someValuesFrom (a:plant)))) Class(a:vegetarian complete intersectionOf( a:animal restriction(a:eats allValuesFrom (complementOf(restriction(a:part_of someValuesFrom (a:animal))))) restriction(a:eats allValuesFrom (complementOf(a:animal))))) Class(a:mad_cow complete intersectionOf( a:cow restriction(a:eats someValuesFrom (intersectionOf(restriction(a:part_of someValuesFrom (a:sheep)) a:brain))))) Class(a:sheep partial a:animal restriction(a:eats allValuesFrom (a:grass)))

17 Berendt: Knowledge and the Web, 1st semester 2014/2015, 17 Examples: Instance inferences (1) Individual(a:Spike type(owl:Thing) value(a:is_pet_of a:Pete)) Individual(a:Pete type(owl:Thing)) ObjectProperty(a:has_pet domain(a:person) range(a:animal)) ObjectProperty(a:is_pet_of inverseOf(a:has_pet))

18 Berendt: Knowledge and the Web, 1st semester 2014/2015, 18 Examples: Instance inferences (2) Individual(a:Daily_Mirror type(owl:Thing)) Individual(a:Nick type(a:male) value(a:drives a:Q123_ABC) value(a:reads a:Daily_Mirror)) Individual(a:Q123_ABC type(a:van) type(a:white_thing)) Class(a:white_van_man complete intersectionOf( a:man restriction(a:drives someValuesFrom (intersectionOf(a:van a:white_thing))))) Class(a:white_van_man partial restriction(a:reads allValuesFrom (a:tabloid)))

19 Berendt: Knowledge and the Web, 1st semester 2014/2015, 19 Examples: Instance inferences (3) Individual(a:Walt type(a:person) value(a:has_pet a:Huey) value(a:has_pet a:Louie) value(a:has_pet a:Dewey)) Individual(a:Huey type(a:duck)) Individual(a:Dewey type(a:duck)) Individual(a:Louie type(a:duck)) DifferentIndividuals(a:Huey a:Dewey a:Louie) Class(a:animal_lover complete intersectionOf( a:person restriction(a:has_pet minCardinality(3))))

20 Berendt: Knowledge and the Web, 1st semester 2014/2015, 20 Examples: Instance inferences (4) Individual(a:Minnie type(a:female) type(a:elderly) value(a:has_pet a:Tom)) Individual(a:Tom type(owl:Thing)) ObjectProperty(a:has_pet domain(a:person) range(a:animal)) Class(a:old_lady complete intersectionOf(a:person a:female a:elderly)) Class(a:old_lady partial intersectionOf( restriction(a:has_pet someValuesFrom (a:animal)) restriction(a:has_pet allValuesFrom (a:cat ))))

21 Berendt: Knowledge and the Web, 1st semester 2014/2015, 21 Agenda OWL: Protégé interface, XML/RDF OWL viewed as a description logics: basics OWL: another syntax (for the examples that follow) OWL inference examples Common problems in using OWL reasoning

22 Berendt: Knowledge and the Web, 1st semester 2014/2015, 22 Properties and existential restrictions Yet another syntax: Read this as intersectionOf (Pizza restriction1 restriction2)

23 Berendt: Knowledge and the Web, 1st semester 2014/2015, 23 Primitive and defined classes

24 Berendt: Knowledge and the Web, 1st semester 2014/2015, 24 Open world reasoning (1)

25 Berendt: Knowledge and the Web, 1st semester 2014/2015, 25 Open world reasoning (2): Is this a Margherita Pizza?

26 Berendt: Knowledge and the Web, 1st semester 2014/2015, 26 Open world reasoning (3): closure restrictions/axioms – what does this exclude?

27 Berendt: Knowledge and the Web, 1st semester 2014/2015, 27 Domain and range restrictions are axioms – or: when should you not use domain/range, but restrictions instead?

28 Berendt: Knowledge and the Web, 1st semester 2014/2015, 28 „and“ and „or“ in logics vs. in natural language, “all“ vs. “some“ - what do these 2 definitions say? Is this the intention? How can it be expressed better?

29 Berendt: Knowledge and the Web, 1st semester 2014/2015, 29 Does „only“ ( allValuesFrom ) imply „some“ ( someValuesFrom )? Is an EmptyPizza a VegetarianPizza?

30 Berendt: Knowledge and the Web, 1st semester 2014/2015, 30 „some not …“ vs. „not some …“: what does this definition say? Is this the intention? How can it be expressed better?

31 Berendt: Knowledge and the Web, 1st semester 2014/2015, 31 Task for the next week n Find 3 ontological statements on the Semantic Web, for example using Sindice. n Paraphrase what they mean. n Find 1 statement involving owl:EquivalentClass. What problems are likely to arise when statements made about this class (with its two names) come from different knowledge sources?

32 Berendt: Knowledge and the Web, 1st semester 2014/2015, 32 Outlook OWL: Protégé interface, XML/RDF OWL viewed as a description logics: basics OWL: another syntax (for the examples that follow) OWL inference examples Common problems in using OWL reasoning Combining SW data: Schema/ontology matching

33 Berendt: Knowledge and the Web, 1st semester 2014/2015, 33 Used sources OWL specification at resp. Difference between OWL Lite, DL, and Full by Ritesh Agrawal (2007) at OWL Abstract Syntax: A short summary here: pp. 10ff.: Bechhofer, S. (2003). OWL Reasoning Examples. pp. 22ff.: Alan L. Rector, Nick Drummond, Matthew Horridge, Jeremy Rogers, Holger Knublauch, Robert Stevens, Hai Wang, Chris Wroe: OWL Pizzas: Practical Experience of Teaching OWL-DL: Common Errors & Common Patterns. EKAW 2004: Picture credits: see PPT „comments“ field