Elena Simperl @SSSC2009, Berkeley, CA.

F d l f  l iFundamentals of ontologiesDefinitions, features, classifications, applications, modelling principlesmodelling principles

Ontology engineeringMethodologies  methods and tools to build  Methodologies, methods and tools to build, manage and use ontologies

*Thanks to Tobias Bürger, Asuncion Gomez Perez and MartinHepp for providing valuable contents to this lecture

A   t l  d fi  th  b i  t   d  l ti  An ontology defines the basic terms and relations comprising the vocabulary  of  a topic area, as well as the rules for combining terms and relations to define  

t i  t  th   b lextensions to the vocabularyNeches, R.; Fikes, R.; Finin, T.; Gruber, T.; Patil, R.; Senator, T.; Swartout, W.R. Enabling 

Technology for Knowledge Sharing. AI Magazine. Winter 1991. 36‐56

An ontology is an explicit specification of a conceptualizationGruber, T. A translation Approach to portable ontology specifications. Knowledge Acquisition. 

Vol  5  1993  199‐220Vol. 5. 1993. 199‐220

A   t l  i    hi hi ll   t t d  t  f t  f  An ontology is a hierarchically structured set of terms for describing a domain that can be used  as a skeletal foundation for a knowledge base

B  Swartout  R  Patil  k  Knight  T  Russ   Toward DistributedUse of Large ScaleOntologiesB. Swartout; R. Patil; k. Knight; T. Russ.  Toward DistributedUse of Large‐ScaleOntologiesOntological Engineering. AAAI‐97 Spring SymposiumSeries. 1997. 138‐148

An ontology provides the means for describing explicitly the conceptualization behind the knowledge represented in a conceptualization behind the knowledge represented in a knowledge baseA. Bernaras;I. Laresgoiti; J. Correra.   Building and ReusingOntologies for Electrical Network Applications ECAI96. 12th European conference onArtificial Intelligence. Ed.  John Wiley

& S  Ltd   8& Sons, Ltd. 298‐302

“An ontology is a formal, explicit specification of a shared conceptualization”

Consensual

Machine-readable

Consensual Knowledge

Abstract model and simplified view of some

Concepts, propertiesrelations, functions,

Studer, Benjamins, Fensel. Knowledge Engineering: Principles and Methods. Data and Knowledge Engineering. 25 (1998) 161-197

simplified view of some phenomenon in the world that we want to represent

constraints, axioms, are explicitly defined

Studer, Benjamins, Fensel. Knowledge Engineering: Principles and Methods. Data and Knowledge Engineering. 25 (1998) 161 197

SUMOSUMO

Modelled knowledge about a specific domainModelled knowledge about a specific domain

DefinesA common vocabularyA common vocabularyThe meaning of termsHow terms are interrelated

Consists of  Conceptualization and implementationConceptualization and implementation

ContainsOntological primitivesOntological primitives

C     i d i   iConcepts are organized in taxonomiesRelations • R: C1 x C2 x ... x Cn-1 x Cn

Functions• F: C1 x C2 x ... x Cn-1 --> Cn

Instances• Elements

Axioms• Sentences which are always true

Issue of the conceptualizationIssue of the conceptualizationUpper‐level/Top‐levelCoreDomainDomainTaskApplicationRepresentationp

Degree of formalityHighly informal: in natural languageS i i f l  i     i d  d  d f   f  l Semi‐informal: in a restricted and structured form of natural languageSemi‐formal: in an artificial and formally defined languageRigorously formal: in a language with formal semantics  theorems Rigorously formal: in a language with formal semantics, theorems and proofs of such properties as soundness and completeness

Thessauri General

Catalog/ID

Thessauri “narrower term”

relationFormal

is-aFrames

(properties)

General Logical

constraints

T / I f l Formal V l DisjointnessTerms/ glossary

Informal is-a

Formal instance

Value Restrs.

Disjointness, Inverse, part-Of

...

Lassila O, McGuiness D. The Role of Frame-Based Representation on the Semantic Web. Technical Report. Knowledge Systems Laboratory. Stanford University. KSL-01-02. 2001.

Application Domain Application Domain RE Ontology Task Ontology

Domain Ontology Domain Task Ontology

EUSA Core Ontology Task Ontology

Top-Level Ontology

BILI

Core Ontology Task Ontology

Representation Ontology

General/Common OntologyITY

O t l i    b  b ilt  i   i  l   ith  i  Ontologies can be built using various languages with various degrees of formality

Natural languageUMLUMLEROWL/RDFSWSMLWSMLFOL...

Th  f li   d th  l  li it th  ki d  f k l d  th t The formalism and the language limit the kind of knowledge that can be representedA domain model is not necessarily a formal ontology only because it is written in OWLit is written in OWL

(defconcept Travel"A journey from place to place"

:is-primitive(:and

(defrelation Pays:is (:function (?room ?Discount)( (Price ?room) (/(*(Price ?room) ?Discount) 100)))(:and

(:all arrivalDate Date)(:exactly 1 arrivalDate)(:all departureDate Date)(:exactly 1

departureDate)(:all companyName String)

(- (Price ?room) (/( (Price ?room) ?Discount) 100))):domains (Room Number):range Number)

(:all singleFare Number)(:at-most singleFare 1))) (defrelation connects"A road connects two different cities"

:arity 3:domains (Location Location)

R dS ti(tellm (AA7462 AA7462-08-Feb-2002) :range RoadSection:predicate ((?city1 ?city2 ?road) (:not (part-of ?city1 ?city2))(:not (part-of ?city2 ?city1))

(tellm (AA7462 AA7462-08-Feb-2002)(singleFare AA7462-08-Feb-2002 300)(departureDate AA7462-08-Feb-2002 Feb8-2002)(arrivalPlace AA7462-08-Feb-2002 Seattle))

( (p y y ))(:or (:and (start ?road ?city1)(end ?road ?city2))

(:and (start ?road ?city2)(end ?road ?city1)))))

K l d   iKnowledge representationOntology models domain knowledge

Semantic annotationSemantic annotationOntology is used as a vocabulary, classification or indexing schema for a collection of itemsindexing schema for a collection of items

Semantic searchOntology is used as a query vocabulary or for gy q y yquery rewriting purposes

ConfigurationOntology defines correct configuration templates

Ontology‐based SearchNeutral Authoring

Ontologies provide the structure for the navigation of the results, support browsing and classification.

Bases for application development as core data model for all applications.

Typical use case in AI

O t l i

Ontologies allow for term disambiguation and query rewriting.

Typical use case in AI.

OntologiesSpecification of software systems and automation of code generation.

Global view on information.

Organization and management of information 

MDA.

SOA.

sources and their interrelation.

Consistency checking.

Ontology‐based SpecificationCommon Access to Information

Source: Jasper & Uschold, 1999.

fQuery formulation.Query rewriting.

dAugmented query processing.

h kSemantic matchmaking.Navigation and browsing.

lVizualization.

WatsonWatsonhttp://watson.kmi.open.ac.uk/Overview.html

Swooglehttp://swoogle.umbc.edu/

Protégé  Ontologiesg ghttp://protegewiki.stanford.edu/index.php/Protege_Ontology_Library#OWL_ontologies

OBO Foundation Ontologieshttp://www.obofoundry.org/

Open Ontology Repositoryhttp://ontolog.cim3.net/cgi‐bin/wiki.pl?OpenOntologyRepository

Manchester Ontology Libraryhttp://owl.cs.manchester.ac.uk/repository/

Ontology Yellow Pageshttp://wg sti2 org/semtech onto/index php/The Ontology Yellow Pageshttp://wg.sti2.org/semtech‐onto/index.php/The_Ontology_Yellow_Pages

AIM@SHAPEhttp://dsw.aimatshape.net/tutorials/ont‐intro.jsp

VoCampsphttp://vocamp.org/wiki/Main_Page

Project management: t lli l i lit t

Domain analysismotivating scenarios, competency questions, existing solutions

Kno

Project management: controlling, planing, quality assurance etc.

Conceptualizationconceptualization of the model, integration and extension of existing solutions

owledge a

Evaluat

Docum

en

Implementationimplementation of the formal model in a representation language

cquisition

tion

ntation

Usage/Maintenanceadaptation of the ontology according to new requirements

Management SupportDevelopment oriented

Pre-development

SchedulingKnowledge acquisition

Environment study Feasibility studyg

Evaluation IntegrationDevelopment

Environment study Feasibility study

Control Documentation

Specification Conceptualization

Merging

Quality

Formalization Implementation

Post-development

Qualityassurance

Configurationmanagement

Maintenance Use Alignment

Historical Background

Enterprise Ontology[U h ld & Ki   ]

CommonKADS[Schreiber et al., 1999]

[Uschold & King, 1995]DILIGENT

[Tempich  2006]IDEF5[Benjamin et al. 1994]

H l l &J hi

[Tempich, 2006]

OTK Holsapple&Joshi[Holsapple & Joshi, 2002]

METHONTOLOGY

OTK[Sure, 2003]

CO4[Euzenat, 1995]

METHONTOLOGY[Gomez‐Perez, 1996]

T l i d hTwo or more people interact and exchangeknowledge in order to build a common, shared ontology in pursuit of a shared   shared ontology in pursuit of a shared,  collective, bounded goal.Interaction may be indirect but required  Interaction may be indirect but required. Argumentation as a common interaction means.Simple contributions not enough  Simple contributions not enough. Bounded goal: beginning and end.Collaborators may have individual goals.Collaborators may have individual goals.

1 Emergence of ideas  In the first phase  new concept ideas are collected in an 1. Emergence of ideas. In the first phase, new concept ideas are collected in an ad‐hoc fashion. This is done using simple tags. 

2. Consolidation in communities. The concept symbols generated in the first phase are re‐used and adapted by the user community. The phase aims at p p y y pextracting concepts from the available tags leading to a common terminology.

3. Formalization. This phase adds taxonomic and ad‐hoc relations to the common terminology yielding lightweight but formal ontologies. 

4. Axiomatization. The final step in the methodology addresses knowledge workers, i.e. ontology engineers, to add axiom leading to a heavy‐weight ontology.

[Braun, 2007]

T i  i       f l  h   Tagging is a very successful approach to organize all sorts of content on the Web.

Approaches to derive formal ontologies from tag clouds are emerging.

There are several tools available for building ontologies using semantic wikis.g g

Serious games to engineer ontologies and annotate contentannotate content.

http://vocamp.org/wiki/Main_Page 

elena.simperl@sti2.at