Semantic Web and Ontology Management

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Semantic Web and Ontology Management

• Tutorial at ACAI Summer School
• Rudi Studer, York Sure,
• Christoph Tempich, Peter Haase
• Institute AIFB, University of Karlsruhe
• FZI Research Center for Information Technologies
  
• Ontoprise GmbH, Karlsruhe

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Agenda

• 900h
• Welcome
• Motivation
• Semantic Web and Ontologies
• 10.30h Coffee Break
• 11.00h
• DILIGENT Methodology
• Ontology Evolution
• Ontology Management in SEKT
• 12.30h Lunch

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Short CV Rudi Studer

• Education
• 1975Diploma in Computer Science at the
  University of Stuttgart
• 1982 Doctors degree in Mathematics and Computer
  Science at the University of Stuttgart
• 1985 Habilitation in Computer Science at the
  University of Stuttgart
• Professional career
• 1977 to 1985 research scientist at the University
  of Stuttgart.
• 1985 to 1989 project leader and manager at the
  Scientific Center of IBM Germany
• Since 1989 full professor of Applied Informatics
  at the University of Karlsruhe

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Short CV Rudi Studer

• Professional Career (2)
• one of the presidents of the FZI Research Center
  for Information Technologies at the University of
  Karlsruhe (www.fzi.de)
• co-founder of the spin-off company ontoprise GmbH
  (www.ontoprise.de)
• Professional activities
• Technical director of the SEKT project
• President of the Semantic Web Science Foundation
• Co-Editor-in-Chief Journal of Web Semantics

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... Semantic Web HISTORY
27. May 1994 Sir Tim Berners-Lee Vision of a
Semantic Web Closing Key Note, 1. Int. WWW
Conference, CERN Adding semantics to
the web involves two things allowing documents
which have information in machine-readable
forms, and allowing links to be created with
relationship values.
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... Semantic Web HISTORY
10.2.2004 Resource Description Framework
(RDF) Web Ontology Language (OWL) become W3C
recommendations
Semantic Web Web Data base technology
Knowledge Representation
Source http//www.zakon.org/robert/internet/tim
eline/
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Semantic Web
The Semantic Web is an extension of the current
web in which information is given well-defined
meaning, better enabling computers and people to
work in co-operation. Berners-Lee et al.,
2001
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Machine accessible meaning (What its like
to be a machine)
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XML
User definable and domain specific markup
HTML
ltH1gtKnowledge Managementlt/H1gt ltULgt ltLIgtTeacher
Rudi Studer ltLIgtStudents Master lt/ULgt
XML
ltcoursegt lttitlegtKnowledge Managementlt/titlegt ltte
achergtRudi Studerlt/teachergt ltstudentsgtMasterlt/stu
dentsgtlt/coursegt
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XML Document labelled tree

• node label attr/values contents

• DTD simple grammars to describe legal trees
• So Why not use XML to represent ontologies?

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XML limitations for semantic markup

• XML per se makes no commitment on
• Domain specific ontological vocabulary
• Ontological modelling primitives
• ? requires pre-arranged agreement on ? ?

• Only feasible for closed collaboration
• agents in a small stable community
• pages on a small stable intranet
• .. not for sharable Web-resources

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XML ? machine accessible meaning
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The semantic pyramid again
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RDF for semantic annotation

• RDF provides metadata about Web resources
• Object -gt Attribute-gt Value triples
• It has an XML syntax
• Chained triples form a graph

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What does RDF Schema add?

• Defines vocabulary for RDF
• Organizes this vocabulary in a typed hierarchy
• Class, subClassOf, type
• Property, subPropertyOf
• domain, range

supervises
Tom
Siggi
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RDF Schema syntax in XML
ltrdfDescription ID"MotorVehicle"gt ltrdftype
resource"http//www.w3.org/...Class"/gt
ltrdfssubClassOf rdfresource"http//www.w3.org/.
..Resource"/gt lt/rdfDescriptiongt ltrdfDescrip
tion ID"Truck"gt ltrdftype resource"http//ww
w.w3.org/...Class"/gt ltrdfssubClassOf
rdfresource"MotorVehicle"/gt lt/rdfDescriptiongt
ltrdfDescription ID"registeredTo"gt
ltrdftype resource"http//www.w3.org/...Property
"/gt ltrdfsdomain rdfresource"MotorVehicle"/
gt ltrdfsrange rdfresource"Person"/gt lt/rdfD
escriptiongt ltrdfDescription IDownedBy"gt
ltrdftype resource"http//www.w3.org/...Property
"/gt ltrdfssubPropertyOf rdfresource"registe
redTo"/gt lt/rdfDescriptiongt
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Conclusions about RDF(S)

• Next step up from plain XML
• (small) ontological commitment to modeling
  primitives
• possible to define lightweight ontologies

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Where are we now?
Further Activities Semantic Web Service
Committee Semantic Web Best Practices
Work in Progress
RFC
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Origin and History

• Ontology in Philosophy
• a philosophical discipline, branch of philosophy
  that deals with the nature and the organisation
  of reality
• Science of Being (Aristotle, Metaphysics, IV, 1)
• Tries to answer the questions
• What characterizes being?
• Eventually, what is being?

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Ontologies in Linguistics

Concept
refers to
evokes
Referent
Form
Stands for
Jaguar
Odwen, Richards, 1923
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Ontologies in Computer Science

• An ontology is an explicit specification of a
  conceptualization. Gruber, 93
• An ontology is a shared understanding of some
  domain of interest. Uschold, Gruninger, 96
• Ontology refers to an engineering artifact
• It is constituted by a specific vocabulary used
  to describe a certain reality, plus
• a set of explicit assumptions regarding the
  intended meaning of the vocabulary.
• Thus, ontologies describe a formal specification
  of a certain domain
• Shared understanding of a domain of interest
• Formal and machine executable model of a domain
  of interest

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Why develop an ontology?

• To make domain assumptions explicit
• Easier to change domain assumptions
• Easier to understand and update legacy data
• To separate domain knowledge from operational
  knowledge
• Re-use domain and operational knowledge
  separately
• A community reference for applications
• To share a consistent understanding of what
  information means

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Types of Ontologies
Guarino, 98
Describe very general concepts like space, time,
event, which are independent of a particular
problem or domain. It seems reasonable to have
unified top-level ontologies for large
communities of users.
Describe the vocabulary related to a generic
domain by specializing the concepts introduced in
the top-level ontology.
Describe the vocabulary related to a generic task
or activity by specializing the top-level
ontologies.
These are the most specific ontologies. Concepts
in application ontologies often correspond to
roles played by domain entities while performing
a certain activity.
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Ontologies - Some Examples

• General purpose ontologies
• WordNet / EuroWordNet, http//www.cogsci.princeton
  .edu/wn
• The Upper Cyc Ontology, http//www.cyc.com/cyc-2-1
  /index.html
• IEEE Standard Upper Ontology, http//suo.ieee.org/
  
• Domain and application-specific ontologies
• RDF Site Summary RSS, http//groups.yahoo.com/grou
  p/rss-dev/files/schema.rdf
• UMLS, http//www.nlm.nih.gov/research/umls/
• RETSINA Calendering Agent, http//ilrt.org/discove
  ry/2001/06/schemas/ical-full/hybrid.rdf
• AIFB Web Page Ontology, http//ontobroker.semantic
  web.org/ontos/aifb.html
• Web-KB Ontology, http//www-2.cs.cmu.edu/afs/cs.cm
  u.edu/project/theo-11/www/wwkb/
• Dublin Core, http//dublincore.org/
• Meta-Ontologies
• Semantic Translation, http//www.ecimf.org/contrib
  /onto/ST/index.html
• Evolution Ontology, http//kaon.semanticweb.org/ex
  amples/Evolution.rdfs
• Ontologies in a wider sense

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Ontologies and their Relatives
General logical constraints
Formal Is-a
Thesauri
Frames
Catalog / ID
Informal Is-a
Formal Instance
Value Restric- tions
Terms/ Glossary
Axioms Disjoint Inverse Relations, ...
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Ontologies and their Relatives (cond)
Front-End
Navigation
Information Retrieval
Sharing of Knowledge
Query Expansion
Ontologies
Queries
Consistency Checking
EAI
Mediation
Reasoning
Back-End
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Menu
Taxonomy
Object
Person
Topic
Document
Researcher
Student
Semantics
Ontology
Doctoral Student
PhD Student
F-Logic
Taxonomy Segmentation, classification and
ordering of elements into a classification system
according to their relationships between each
other
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Menu
Thesaurus
Object
Person
Topic
Document
Researcher
Student
Semantics
PhD Student
Doktoral Student
Ontology
F-Logic
similar
synonym

• Terminology for specific domain
• Graph with primitives, 2 fixed relationships
  (similar, synonym)
• originate from bibliography

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Menu
Topic Map
Object
Person
Topic
Document
Researcher
Student
Semantics
synonym

• Topics (nodes), relationships and occurences (to
  documents)
• ISO-Standard
• typically for navigation- and visualisation

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Ontology (in our sense)
Object
described_in
Person
Topic
Document
writes
Researcher
Student
instance_of
Tel

• Major Paradigms Logic Programming, Description
  Logic
• Standards RDF(S) OWL

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Ontology Annotation
cooperate_with
Ontology
rdfsrange
rdfsdomain
AcademicStaff
rdfssubClassOf
rdfssubClassOf
PhD Student
AssProf
Links have explicit meanings!