July 2002 CSM2002, AB + HS 1

Ontologies to structure models and modeling tasks

Adrie J.M. Beulens and Huub Scholten Wageningen Universiteit, Toegepaste Informatiekunde

July 2002 CSM2002, AB + HS 2

The Message

An ontology is a body of structured knowledge, shared by all stakeholders for (re-)use by man and computer

To define knowledge on modeling:

Ontology of the modeling process (modeling tasks) To define knowledge on the problem

Ontology of the object system To develop and exchange models : need for a common

model representation format --> develop first:

Ontology of (quantitative, algebraic) models

July 2002 CSM2002, AB + HS 3

Topics Introduction Why ontologies? What are ontologies? Why ontologies to solve modeling problems An overall picture Discussion

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Introduction

20 years ago:– Ontology: esoteric part of philosophy, about being, about what can

be mentioned (Gruninger & Lee, 2002)– Aristotele distinguished in his system theoretical philosophy

(physics, ontology, logics) and practical philosophy (ethics, politics, poetics).

– The ontology studies ‘what is’ as such , their nature, characteristics and mutual relations

Now (May 2002): – Google finds 310.000 websites on ‘ontology’– Term borrowed from knowledge engineering– examples

July 2002 CSM2002, AB + HS 5

Example sites on ‘Ontology’ Gene ontology consortium

What is an ontology?

Ontology.Org - enabling virtual business

Ontology - descriptive and formal

The ontology page

Buffalo ontology site

W3C web ontology (webont) working group

KR/DB conferences and journal cfps

Enterprise project: The enterprise ontology

Kbs/ontology projects worldwide

July 2002 CSM2002, AB + HS 6

Why ontologies? (1) A help in structuring complex definitions and arrive at

shared understanding Here:

– what elements are needed/allowed in a model definition– what knowledge of an object system is required/essential/relevant

to solve a problem using models– what knowledge/expertise on modeling is required for a Good

Modeling Practice

Used for:– defining knowledge in general: Internet/WWW– defining protocols in medics and other guidelines– hierarchical knowledge (ecosystems, car repair, ….)

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Why ontologies? (2)

Communication:– Between people– Between computers/systems– Between man and computer

Re-use of knowledge Make assumptions Explicit Ordering and structuring of knowledge Analysing of knowledge

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What are ontologies? Two definitions:

– Gruber 1994 (for AI systems):

A formal specification of a shared conceptualisation

(Concept = what “exists” is that which can be represented)

– Borst, 1997:

An ontology is a formal specification of a shared conceptualisation

Ontologies consists of– Concepts (things you can discuss)

– Relations between concepts (consists of, must be preceded by, etc.)

– Functions (relations with 1 result)

– Instants (specific concept, not generic)

– Axiomata (knowledge on concepts/relations that can be checked on its logics)

July 2002 CSM2002, AB + HS 9

Representations of ontologies Languages:

– Old: ontolingua , KIF, OKBC, etc. – New (xml-based): XOL, RDF, OIL, DAML+OIL

Tools:– Old: server in Stanford University Knowledge Systems Laboratory– New:

• Protegé2000

• OilEd

• OntoEdit

Examples ‘formats’: internet

July 2002 CSM2002, AB + HS 10

The role of ontologies in MBDS

MB-DS = Model Based Decision Support Discussed here ontologies on

– Problem/object-system ontology– Model ontology– Modeling ontology– How are these related

Example (greenhouse): diagram

has-variables

has-subgraph

has-expressions

http://www.ato.nl/onto/dyn_gra_01

http://www.ato.nl/onto/Concrete_floor_22

http://www.ato.nl/onto/dyn_el_01

http://www.ato.nl/onto/var_11http://www.ato.nl/onto/expr_11

has_elements

component

dynamics_graph

typetype

type

Example (greenhouse): ontology in XML/RDF

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns="http://www.ato.nl/onto/schema#">

<rdf:Description rdf:about="#Concrete_floor_22"> <rdf:type rdf:resource="#component"> <imms:has_subgraph rdf:resource="#dyn_gra_01"/> </rdf:Description>

<rdf:Description rdf:about="#dyn_gra_01"><rdf:type rdf:resource="#dynamics_graph"><imms:has_elements rdf:resource="#dyn_el_01"/>

</rdf:Description>

<rdf:Description rdf:about="#dyn_el_01" type="capacitor"> <rdf:type rdf:resource="#dynamics_element"> <imms:has_expressions rdf:resource="#expr_11"/> <imms:has_variables rdf:resource="#var_11"/> </rdf:Description></rdf:RDF>

July 2002 CSM2002, AB + HS 13

Problem/object system ontology Making explicit:

– What we are interested in in the OS + reason (problem)– Application domain (which knowledge / science / theories etc.)– Problem owner– Problem:

• type of application– planning– design– research– operational management

• description

– Existing models

July 2002 CSM2002, AB + HS 14

Model ontology What is a model ontology?

– ontology of concepts and mutual relations describing the structure of models (within a modeling paradigm?)

What part of a OS ontology is reflected in a model (paradigm) ontology and how is it reflected?

Examples of model ontologies:– Jan Top (ATO): physical models– to be done (Huub Scholten)

• ontology on eco-physiological processes of bivalves (+instances)

– RWS/RIKZ: • generic model for estuarine ecosystems

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Modeling ontology

Examples of preliminary steps towards a modeling ontology:– GMP handbook– NEN-norms for modeling water management in the Netherlands

Process oriented: tasks and mutual dependencies– name of task– what? definition– who? modeller, client stakeholder– how? (advice on) methods– which problems to be expected?pitfalls & sensitivities

MB-DS-ontology

model ontology- what elements in a model- what meta-data needed- common representation format- other requirements

object system ontology- application domain- which domain knowledge included- problem owner- type of application     design     planning,      research,      operational management- problem description- defining object system- which existing models?   

modeling ontology- GMP- decompostion of tasks- interelation of tasks

modeldefinition

object systemdefinition

modelingguidelines

problemdefinition

problemsolving

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Projects related to MB-DS-ontology

Dutch GMP handbook Norms for model use for Dutch water management HarmoniQuA ATO AMEPS

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Discussion

How consistent is the presented approach?– Object system ontology– Model ontology– Modeling ontology

How to deal with domain specific aspects? Representation formats important?