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)


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)


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


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


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• …


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)


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


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


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


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)


Information objects: a foundation for content description [a semiotic ontology design pattern]


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


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”


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)


IA(L)

MD(L)

IB(L)

Area of falseagreement!

Why precision is important


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


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…

…


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.

Towards a Reference Library of Upper Ontologies the DOLCE point of view Nicola Guarino Head,...

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