ontology engineering: ontology construction ii

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  • 1. Ontology construction II Course Ontology Engineering 1

2. Overview Part-whole relations Vocabulary representation with SKOS Examples of commonly-used ontologies 2 3. PART-WHOLE RELATIONS 4. Part-whole relations Mereology = theory of part-whole meros is Greek for part Common in many domains Human body, cars, installations, documents Different from the subclass/generalizationrelation No built-in modeling constructs in OWL Different types of part-whole relations exist With important semantic differences 4 5. UML Aggregation Aggregation denotes a binary associationin which one side is an "assembly" and theother side a "part". "Assembly" and "part" act as predefinedroles involved in the aggregationassociation. Cardinality of a part can be defined precisely one; optional (0-1); many, ... No semantics in UML! 5 6. Aggregation example in UML0-1 audioCD playersystem record 0-1 player 0-1tuner 0-10-1 2,4amplifiertape deckhead speakerphones6 7. UML Composition Sub-type of aggregation Existence of part depends on aggregate 7 8. Aggregation vs. generalization Similarities: Tree-like structure Transitive properties Differences: AND-tree (aggregation) vs. OR-tree(generalization) instance tree (aggregation) vs. class tree(generalization) 8 9. Examples: partOf or subClassOf? House Building Brick House Antique book Antique book collection Silvio Married Couple Veronica Married Couple Hand Body part Finger Hand 9 10. Confusion with non-compositional relations Temporal topological inclusion The customer is in the store, but not part of it Classification inclusion A Bond movie is an instance of film but part of my film collection Attribution The height and width of a ship are not part of the ship Attachment A wrist watch is not part of the wrist Ownership I own a bicycle but it is not part of me10 11. Representing part-whole relations11 12. Representing part-wholerelations Part-whole relation is transitive If A is part of B and B is part of C then A ispart of C But see the caveats later on Usually there is a a need to distinguish: Part in a transitive sense Direct part 12 13. Basic scheme Define a property e.g. partOf and(usually needed) the inverse hasPart Define a subproperty of partOf torepresent direct parts, e.g. partOfDirect Choose the primary property forexpressing part-whole: part of orhasPart? partOf is generally more intuitive. Why? 13 14. Transitivity A subproperty of a transitive property isnot by definition transitive Make sure you understand why Example: direct-part properties are nottransitive14 15. Part-whole specification withindividuals:Amsterdam a :InhabitatedPlace ;:partOf :North-Holland .:North-Holland a :Province ;:partOf :Netherlands .:Place a owl:Class ;rdfs:subClassOf[ a owl:Restriction ;owl:onProperty :partOf ;owl:allValuesFrom :Place ] . 15 16. Part-whole specification withclassesAudioSystem hasPart someValuesFrom Amplifier someValuesFrom Loudspeaker someValuesFrom InputSystem[assume CD, tuner and cassette playerdefined as subclasses of input system] 16 17. Characteristics of part-wholerelations Vertical relationships Existence dependency between whole andpart Feature dependencies: Inheritance from part to whole: defective Inheritance from whole to part: owner Systematic relation: weight whole = sum weight parts Horizontal relationships Constraints between parts17 18. Types of part whole relations 18 19. Types of part-whole relationsBased on three distinctions1. Configurability Functional/structural relation with the other partsor the whole yes/no2. Homeomerous Parts are same kind as the whole yes/no3. Invariance Parts can be separated from the whole19 20. Component-integral Functional/structural relation to the whole Parts can be removed and are differentfrom whole Organization of the parts Examples: car wheels, film scenes N.B. difference between wheel and carwheel20 21. Material-object Invariant configuration Examples: A bicycle is partly iron Wine is partly alcohol Human body is partly water The made-off relation Relation between part and whole is notknown 21 22. Portion-object Homeomeric configuration of parts Examples: A lice of bread is part of a loaf of bread A sip of coffee is part of a cup o coffee Portions can be quantified with standardmeasures (liter, gram, ..) Homeomeric: a sip of coffee is coffee (buta bicycle wheel is not a bicycle) Ingredients of portion and object are the same 22 23. Place-area Homeomeric invariant configuration Examples: North-Holland is part of The Netherlands The Mont Blanc peak is part of the Mont Blancmountain The head is part of the human body (?!) Typically between places and locations 23 24. Member-bunch No configuration, no invariance, nothomeomeric Members of a collection Examples: A tree is part of a wood The hockey player is part of a club Differentiate from classification-basedcollections A tree is a member of the class of trees 24 25. Member-partnership Same as member-bunch, but invariant If a part is removed, the whole ceases toexist Examples: Bonny and Clyde Laurel and Hardy A married couple25 26. Example: types of part of relations Vitamin Orange Branch Tree Student the class of 02 Book library Chair Faculty Board Engine Car Artuicle - newspaper 26 27. Transitivity of part-whole types Transitivity does not (necessarily) holdwhen traversing different types of part-whole relation I am a member of a club (member-bunch) My head is part of me (place-area) But: my head is not a part of the club 27 28. Practical example ofontology modelling 28 29. Use case:SelectionCommittee a owl:Class ; rdfs:subClassOf [ a owl:Restriction ; owl:onProperty :committeeMember ; owl:allValuesFrom :Person] . How can we define that a selection committeemust have two female members?29 30. Qualified cardinality restrictions(QCRs) Restriction on the number of values of acertain type (hence qualified) owl:someValuesFrom is an example of sucha constraint cardinality of 1 or more of a certain type ofvalue Typically used to specify the componenttypes in some part-of structure30 31. Workaround for QCRs1. Define a subproperty of the property on which you want to define a QCR2. Define a value constraint (using either owl:allValuesFrom or rdfs:range) and a cardinality constraint on the subproperty Cumbersome for complex part-wholerelations QCR constructs in OWL2 31 32. Example workaround:SelectionCommittee a owl:Class rdfs:subClassOf [ a owl:Restriction ; owl:onProperty :committeeMemberFemale ; owl:allValuesFrom :FemalePerson ] ; rdfs:subClassOf [ a owl:Restriction ; owl:onProperty :committeeMemberFemale ; owl:minCardinality "2"^^xsd:int] . 32 33. Literature Simple part-whole relations in OWL Ontologies Six Different Kinds of Composition (A foundation for composition)33 34. Classroom exercise "Bitterness" In certain combinations and minimum concentrations one or more amino acids can cause bitterness. Amino acids are divided into three groups: Group I, II and III. Every amino acid has a unique chemical formula.34 35. SKOS &VOCABULARIES 36. Overview Commonly used schemas about: Thesauri (SKOS) People and what they do and like (FOAF) Finding documents (Dublin Core) Time Provenance36 37. Thesauri (and vocabularies) Standard terminology in a particulardomain Developed by a community over years ISO standard for thesauri Starting point for ontologies enrichment 37 38. Example thesauri WordNet: lexical resourcehttp://wordnet.princeton.edu/cgi-bin/webwn Getty thesauri AAT: Art & Architecture Thesaurus TGN: Thesaurus of Geographic Names ULAN: Union List of Artist Names Iconclasshttp://www.iconclass.nl MeSH: Medical Subject Headings 38 39. ISO standard for representingthesauri Term Descriptor / Preferred term (USE) Non-descriptor / Non-preferred term (UF) Hierarchical relation between terms Broader/narrower term (BT/NT) Association between terms (RT) 39 40. SKOS:pattern for thesaurus modeling Based on ISO standard RDF representation Documentation: http://www.w3.org/TR/swbp-skos-core-guide/ Base class: SKOS Concept40 41. Classes versus Concepts skos:Concepts are subjects used to indexthings, while rdfs:Classes are sets of thingsthemselves Apart from the meaning of a subject, the ordering ofskos:Concepts can also have to do with howdocuments are grouped. A skos:Concept can correspond to both instanceand class The narrower skos:Concept can be of a differenttype than its broader skos:Concept 41 42. Multi-lingual labels forconcepts 42 43. Difference between WordNetand SKOS 43 44. Documenting concepts 44 45. Semantic relation:broader and narrower No subclass semantics assumed! 45 46. broader vs subClassOf Broader is more generic than subClassOf Broader can be Generic (subclass or type) Partitive (structural, location, membership,etc.) Topic implication (e.g. cow milk under cows) 46 47. Semantic relations:related Symmetric relation 47 48. Facets Thesauri are often structured into facets,high-level groups of similar concepts Objects, People, Places, Events, etc. Facets typically correspond to fields thatare useful in a fielded search engine Subject, Author, Publisher, etc. In SKOS a facet can be modeled withskos:ConceptScheme 48 49. Defining the top level of thehierarchy49 50. Collections:role-type trees50 51. COMMON ONTOLOGIES 52. Friend of a Friend (FOAF) Describing people: names depictions friends, acquaintances, relations organizations e-mail addresses webpages ... see http://xmlns.com/foaf/spec/52 53. Agents: People and Groups53 54. FOAF Basics54 55. Agent identity When are two Agents the same? definitely when they have the same URI or openID probably when they have the same e-mail address...owl:InverseFunctionalProperty? maybe when they have the same name...William of Orange (I the Silent? III of England? theBishop? of Beax? the pigeon in WWII?) AAA, so you have to do disambiguation, alsoca