This document provides an overview of ontology construction and modeling concepts. It discusses part-whole relations including different types like component-integral, material-object, and place-area relations. It also covers representing part-whole relations in OWL and using workarounds for qualified cardinality restrictions. Additionally, it introduces commonly used schemas and ontologies for modeling vocabularies with SKOS, describing people with FOAF, documenting resources with Dublin Core, and representing time.

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/generalization
relation
• No built-in modeling constructs in OWL
• Different types of part-whole relations exist
– With important semantic differences
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5. UML Aggregation
• Aggregation denotes a binary association
in which one side is an "assembly" and the
other side a "part".
• "Assembly" and "part" act as predefined
roles involved in the aggregation
association.
• Cardinality of a part can be defined
– precisely one; optional (0-1); many, ...
• No semantics in UML!
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6. Aggregation example in UML
0-1 audio
CD player system
record 0-1
player
0-1
tuner
0-1 0-1 2,4
amplifier
tape deck head speaker
phones
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7. UML Composition
• Sub-type of aggregation
• Existence of part depends on aggregate
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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)
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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
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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 me
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11. Representing part-whole
relations
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12. Representing part-whole
relations
• Part-whole relation is transitive
– If A is part of B and B is part of C then A is
part of C
– But see the caveats later on
• Usually there is a a need to distinguish:
– Part in a transitive sense
– Direct part
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13. Basic scheme
• Define a property e.g. partOf and
(usually needed) the inverse hasPart
• Define a subproperty of partOf to
represent direct parts, e.g. partOfDirect
• Choose the primary property for
expressing part-whole: part of or
hasPart?
– partOf is generally more intuitive. Why?
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14. Transitivity
• A subproperty of a transitive property is
not by definition transitive
– Make sure you understand why
• Example: direct-part properties are not
transitive
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15. Part-whole specification with
individuals
: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 with
classes
AudioSystem hasPart
someValuesFrom Amplifier
someValuesFrom Loudspeaker
someValuesFrom InputSystem
[assume CD, tuner and cassette player
defined as subclasses of input system]
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17. Characteristics of part-whole
relations
• Vertical relationships
– Existence dependency between whole and
part
– 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 parts
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18. Types of part‐ whole
relations
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19. Types of part-whole relations
Based on three distinctions
1. Configurability
 Functional/structural relation with the other parts
or the whole yes/no
2. Homeomerous
 Parts are same kind as the whole yes/no
3. Invariance
 Parts can be separated from the whole
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20. Component-integral
• Functional/structural relation to the whole
• Parts can be removed and are different
from whole
• Organization of the parts
• Examples: car wheels, film scenes
• N.B. difference between “wheel” and “car
wheel”
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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 not
known
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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 standard
measures (liter, gram, ..)
• Homeomeric: a sip of coffee is coffee (but
a bicycle wheel is not a bicycle)
– Ingredients of portion and object are the same
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23. Place-area
• Homeomeric invariant configuration
• Examples:
– North-Holland is part of The Netherlands
– The Mont Blanc peak is part of the Mont Blanc
mountain
– The head is part of the human body (?!)
• Typically between places and locations
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24. Member-bunch
• No configuration, no invariance, not
homeomeric
• Members of a collection
• Examples:
– A tree is part of a wood
– The hockey player is part of a club
• Differentiate from classification-based
collections
– A tree is a member of the class of trees
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25. Member-partnership
• Same as member-bunch, but invariant
• If a part is removed, the whole ceases to
exist
• Examples:
– Bonny and Clyde
– Laurel and Hardy
– A married couple
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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
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27. Transitivity of part-whole types
• Transitivity does not (necessarily) hold
when 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
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28. Practical example of
ontology modelling
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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 committee
must have two female members? 29

30. Qualified cardinality restrictions
(QCRs)
• Restriction on the number of values of a
certain type (hence “qualified”)
• owl:someValuesFrom is an example of such
a constraint
– cardinality of 1 or more of a certain type of
value
• Typically used to specify the component
types in some part-of structure
30

31. Workaround for QCRs
1. Define a subproperty of the property on
which you want to define a QCR
2. Define a value constraint (using either
owl:allValuesFrom or rdfs:range) and a
cardinality constraint on the subproperty
• Cumbersome for complex part-whole
relations
• 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] .
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33. Literature
• Simple part-whole relations in OWL Ontologies
• Six Different Kinds of Composition
• (A foundation for composition)
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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.
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35. SKOS &
VOCABULARIES

36. Overview
• Commonly used schemas about:
– Thesauri (SKOS)
– People and what they do and like (FOAF)
– Finding documents (Dublin Core)
– Time
– Provenance
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37. Thesauri (and vocabularies)
• “Standard” terminology in a particular
domain
• Developed by a community over years
• ISO standard for thesauri
• Starting point for ontologies
– enrichment
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38. Example thesauri
• WordNet: lexical resource
http://wordnet.princeton.edu/cgi-bin/webwn
• Getty thesauri
– AAT: Art & Architecture Thesaurus
– TGN: Thesaurus of Geographic Names
– ULAN: Union List of Artist Names
• Iconclass
http://www.iconclass.nl
• MeSH: Medical Subject Headings
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39. ISO standard for representing
thesauri
• 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 Concept
40

41. Classes versus Concepts
• skos:Concepts are “subjects” used to index
things, while rdfs:Classes are sets of things
themselves
– Apart from the meaning of a subject, the ordering of
skos:Concepts can also have to do with how
documents are grouped.
• A skos:Concept can correspond to both instance
and class
• The narrower skos:Concept can be of a different
type than its broader skos:Concept
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42. Multi-lingual labels for
concepts
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43. Difference between WordNet
and SKOS
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44. Documenting concepts
44

45. Semantic relation:
broader and narrower
• No subclass semantics assumed!
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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)
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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 that
are useful in a fielded search engine
– Subject, Author, Publisher, etc.
• In SKOS a facet can be modeled with
skos:ConceptScheme
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49. Defining the top level of the
hierarchy
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50. Collections:
role-type trees
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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 Groups
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54. FOAF Basics
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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? the
Bishop? of Beax? the pigeon in WWII?)
• AAA, so you have to do disambiguation, also
called “smushing”
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56. FOAF Personal Info
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57. FOAF Documents
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58. Dublin Core
• A basic schema to improve resource
discovery on the web, i.e. finding stuff.
• Consists of 15 basic elements that are all
optional, extensible, and repeatable.
• International and interdisciplinary.
• see http://purl.org/dc/
• Newest version: 1.1
http://dublincore.org/documents/dces/
58

59. Dublin Core 1.0 Elements
– Title – Format
– Creator – Identifier
– Subject – Source
– Description – Language
– Publisher – Relation
– Contributor – Coverage
– Date – Rights
– Type think of possible links with: FOAF, SKOS,
Creative Commons, MPEG-7, XML Schema,
RSS, etc. Facets? 59

60. Element Refinement
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61. Provenance Definition
• Oxford English Dictionary:
– the fact of coming from some particular source or
quarter; origin, derivation
– the history or pedigree of a work of art, manuscript,
rare book, etc.;
– concretely, a record of the passage
of an item through its various
owners.
• The provenance of a piece of data is the
process that led to that piece of data

62. Open Provenance Model
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63. Time ontology
• Time point versus time interval
– View point as special case of an interval with
identical start and end
• Representation of time and duration
concepts
• See
http://www.w3.org/TR/owl-time/
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64. Allen’s time relations
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