Towards a Reference Library of Upper Ontologies the DOLCE point of view Nicola Guarino Head,...
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Transcript of Towards a Reference Library of Upper Ontologies the DOLCE point of view Nicola Guarino Head,...
Towards a Reference Library of
Upper Ontologiesthe DOLCE point of view
Nicola GuarinoHead, Laboratory for Applied Ontology
Institute for Cognitive Sciences and Technology,National Research Council
Trento, Italy
Thanks to all LOA people!
www.loa-cnr.it
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 2
Summary
1. Lightweight ontologies vs. axiomatic ontologies2. Why a Reference Library of (axiomatic) Upper
Ontologies3. What might the library look like4. How to build such a library: a common framework
• A common minimal vocabulary (meta-ontology?)• A common strategy to elicit the (hidden) assumptions
behind each UO• Common guidelines to express Ontology Design
Rationale• Common metrics to compare ontologies
5. How to evaluate the practical utility of the library and of the single modules.
6. (DOLCE’s basic choices)
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 3
Lightweight ontologies vs. axiomatic ontologies different roles of ontologies
• Lightweight ontologies• Intended meaning of terms mostly known in advance• Taxonomic reasoning is the main ontology service• Limited expressivity• On-line reasoning (stringent computational requirements)
• Axiomatic ontologies• Negotiate meaning across different communities• Establish consensus about meaning of a new term within a
community• Explain meaning of a term to somebody new to community• Higher expressivity required to express intended meaning• Off-line reasoning (only needed once, before cooperation
process starts)
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 4
When are axiomatic ontologies useful?
1. When subtle distinctions are important
2. When recognizing disagreement is important
3. When rigorous referential semantics is important
4. When general abstractions are important
5. When careful explanation and justification of
ontological commitment is important
6. When mutual understanding is important.
Why a Reference Library of Upper Ontologies
• Understand disagreements• Maximize agreements• Promote interoperability
• A starting point for building new ontologies
• A reference point for easy and rigorous comparison
among different ontological approaches
• A common framework for analyzing, harmonizing and
integrating existing ontologies and metadata standards
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 6
The WFOL architecture (WonderWeb FP5 project)
Top
Bank
Law
4D
3D
Single VisionSingle Module
Formal LinksBetween Visions & Modules
Space ofontological
choices
Space of application
areas
Mappings withLexicons
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 7
A common minimal vocabulary(meta-ontology?)
• What is an ontology• Common terms
• Property vs. relation• Property vs. quality (harder…)• Primitive/defined relation• Conceptual relation vs. extensional relation• …
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 8
Common strategy to elicit hidden assumptions
• Systematically explore hidden intra- and inter-categorial relationships
• How is subprocess related to part?• What are the possible relations within processes?
• Use general issues of formal (philosophical) ontology to elicit the assumptions made (possibly by means of simple NL questions)
• Common examples (such as the statue and the clay…)
• Exploit formal meta-properties (OntoClean-like)
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 9
Formal Ontological Analysis
• Theory of Essence and Identity
• Theory of Parts (Mereology)
• Theory of Wholes
• Theory of Dependence
• Theory of Composition and Constitution
• Theory of Properties and Qualities
The basis for a common ontology vocabulary
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 10
Common guidelines to express ontology design rationale
• Identify issues
• List possible alternatives
• Carefully justify and position the choices made with respect to
possible alternatives
• Basic options should be clearly documented
• Clear branching points should allow for easy comparison of
ontological options
• Tradeoffs with respect to:
• Choice of domain
• Choice of relevant conceptual relations
• Choice of primitives
• Choice of axioms
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 11
Comparing ontolgoies: precision and coverage
Low precision, max coverage
Less good
Low precision, limited coverage
WORSE
High precision, max coverage
Good
Max precision, limited coverage
BAD
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 12
Evaluating Upper Ontologies
• Methodology-oriented evaluation• Impact on principles and best practices for
conceptual modeling
• Application-oriented evaluation• Impact on the development of domain ontologies• Impact on the adaptability of domain ontologies
to different domains
• Cognitive and linguistic evaluation• Impact on multilingual linguistic resources• Experiments based on linguistic corpora• Psychological experiments on cognitive adequacy
Aldo Gangemi’s contribution
• Ontology patterns• Role of socially constructed entities (D&S)
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 14
Information objects: a foundation for content description [a semiotic ontology design pattern]
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 15
Qualities in DOLCE: the basic pattern
Color of rose1 Red421Rose1
Inheres
Has-quale
Rose Color
Color-space
Red-obj
Quality
Red-region
Has-part
Has-part
Quality attribution Quality space
q-location
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 16
Concepts and descriptions
• Reify social concepts to be able to predicate on themSocial concepts and roles as first-class-citizens
CN(x): “x is a social concept”
• Reify contexts or concept definitions, called here descriptionsDeal with the social, relational, and contextual nature
of social conceptsDS(x): “x is a description”DF(x,y): “the concept x is defined by the
description y” US(x,y): “the concept x is (re)used in the
description y
• Introduce a temporalized classification relation to link concepts to the entities they classifyAccount for the dynamic behavior of social concepts
CF(x,y,t): “at the time t, x is classified by the concept y”
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 17
Underlying assumptions• Descriptions:
• are created by intentional agents at the time of their first encoding in an expression of a ‘public’ language
• cease to exist when their last physical support ceases to exist
• have a unique semantic content (different, but semantically equivalent, expressions can be associated to the same description)
• have an internal structure intimately related to the logical structure of their semantic contents; partially accounted by means of the predicate US
• Concepts:• are statically linked to descriptions: they
cannot change their definitions• inherit the temporal extension of their
definitions
Extra slides
Ontology
Ontologies and intended meaning
Language L
Conceptualization C
(relevant invariants across situations: D,
)
Intended models IK(L)
State of affairsState of affairsSituations
Ontological commitment K
Tarskian interpretatio
n I
Ontology models IK(L)
Models MD(L)
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 20
IA(L)
MD(L)
IB(L)
Area of falseagreement!
Why precision is important
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 21
DOLCEa Descriptive Ontology for Linguistic and Cognitive Engineering
• Strong cognitive/linguistic bias: • descriptive (as opposite to prescriptive) attitude• Categories mirror cognition, common sense, and the lexical
structure of natural language.
• Emphasis on cognitive invariants• Categories as conceptual containers: no “deep” metaphysical
implications• Focus on design rationale to allow easy comparison with
different ontological options• Rigorous, systematic, interdisciplinary approach• Rich axiomatization
• 37 basic categories• 7 basic relations• 80 axioms, 100 definitions, 20 theorems
• Rigorous quality criteria• Documentation
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 22
DOLCE’s basic taxonomy
EndurantPhysical
Amount of matterPhysical objectFeature
Non-PhysicalMental objectSocial object
…Perdurant
StaticStateProcess
DynamicAchievementAccomplishment
QualityPhysical
Spatial location
…Temporal
Temporal location
…Abstract
AbstractQuality region
Time regionSpace regionColor region…
…
Upper Ontology Summit, March 14-15, 2006 www.loa-cnr.it 23
DOLCE's Basic Ontological Choices
• Endurants (aka continuants or objects) and Perdurants (aka occurrences or events)
• distinct categories connected by the relation of participation.
• Qualities
• Individual entities inhering in Endurants or Perdurants
• can live/change with the objects they inhere in
• Instance of quality kinds, each associated to a Quality Space representing the "values" (qualia) that qualities (of that kind) can assume. Quality Spaces are neither in time nor in space.
• Multiplicative approach
• Different Objects/Events can be spatio-temporally co-localized: the relation of constitution is considered.