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13.12.2005 13.12.2005 1
Intelligent Systems
Lecture 24
Ontologies. Semantic WEB
(based on presentation of Forschungszentrum Informatik at the University of Karlsruhe, Germany)
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Definitions
• An ontology is a specification of a conceptualization
• An ontology is a description (like a formal specification of a program) of the concepts and relationships that can exist for an agent or a community of agents.
• Purpose of enabling knowledge sharing and reuse. In that context, an ontology is a specification used for making ontological commitments.
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Definitions (2)• The subject of ontology is the study of the categories of
things that exist or may exist in some domain.• The product of such a study, called an ontology, is a
catalog of the types of things that are assumed to exist in a domain of interest D from the perspective of a person who uses a language L for the purpose of talking about D.
• The types in the ontology represent the predicates, word senses, or concept and relation types of the language L when used to discuss topics in the domain D. An uninterpreted logic, such as predicate calculus, conceptual graphs, or KIF, is ontologically neutral. It imposes no constraints on the subject matter or the way the subject may be characterized. By itself, logic says nothing about anything, but the combination of logic with an ontology provides a language that can express relationships about the entities in the domain of interest.
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Definitions (2)• An informal ontology may be specified by a catalog of types
that are either undefined or defined only by statements in a natural language. A formal ontology is specified by a collection of names for concept and relation types organized in a partial ordering by the type-subtype relation. Formal ontologies are further distinguished by the way the subtypes are distinguished from their supertypes: an axiomatized ontology distinguishes subtypes by axioms and definitions stated in a formal language, such as logic or some computer-oriented notation that can be translated to logic; a prototype-based ontology distinguishes subtypes by a comparison with a typical member or prototype for each subtype. Large ontologies often use a mixture of definitional methods: formal axioms and definitions are used for the terms in mathematics, physics, and engineering; and prototypes are used for plants, animals, and common household items
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Agenda13.12.2005
• Introduction & Motivation
• Introduction - Semantic Web
• Semantic Web Applications
• Semantic Web Technology
• Next Steps
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KnowledgeManagement
Ontologies andMetadata
MachineLearning
Web Technologies
and Standards
E-Learning Data, TextWeb Mining
InformationExtraction
Web PortalsSearch engines
Metadata-drivenApplications
BasicTechnologies
ApplicationFields
Application fields and technologies
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Motivation
• WWW is a success, measured in
– the number of users
– the number of available documents
• Goal-driven access to information is problematic, because Web content has to be interpreted, combined and processed by humans.
• We are currently on the way to a next generation Web, building on the existing WWW - the Semantic Web which will make contents also for machines accessible and interpretable !
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Arpanet Internet/WWW Semantic Web
1965 1985 20001975 1995
PacketsObjects
Concepts
2005
...
On the Way to a Global Information Structure
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Agenda13.12.2005
• Introduction & Motivation
• Introduction - Semantic Web
• Semantic Web Applications
• Semantic Web Technology
• Next Steps
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“Information Management: A Proposal“,Tim Berners-Lee, CERN,
1989
The Origin of the WWW
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Semantic Web – Bringing the Web to its Full Potential
HTML mit Hyperlinks
Relational
Metadata
URI-SHA
URI-STEFAND
URI-DAMLPROJWORKS-IN
COOPERATES-WITH
WORKS-IN
„ Darpa Agent Markup Language“
PROJECT
RESEARCHER
PERSON
subClassOf
rangedomain
Ontology
TOP
COOPERATESWITH
WORKS-IN
NAME domaindomain
range
NAME
subClassOf
subClassOf
SYMMETRIC
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Ontologies
• In its classical sense ontology is a philosophical discipline.
• In Computer Science: Formal specification of a domain of interest in the form of a concept system
• Targets:
– Shared understanding of a domain of interest
– Formal description of the meaning of terms and relations
– Machine executable (e.g. query for all relations of the concept „HOTEL“)
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• Metadata are „data about data“, e.g.– Library classification systems– The Yahoo! Categorization– Microsoft Office Document Properties
• Metadata in the Semantic Web is complex structured (based on predefined ontologies):
Relational Metadata
http://www.w3c.org/http://www.w3c.org
http://www.w3.org/Home/Lassilahttp://www.w3.org/ Lassila
Ora LassilaOra Lassila
s:Name
s.Organizations.
s:Personrdf:type
rdf:type
s:email
s:worksAt
s:email
s:Name
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Agenda13.12.2005
• Introduction & Motivation
• Introduction - Semantic Web
• Semantic Web Applications
– Skills & Human Resources
– Semantic Intranet Portals
– Interoperability in Tourism
– Web Services
– Virtual Museum
• Semantic Web Technology
• Next Steps
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Ontologies/Metadata in Human Resources
• Usage of skill ontologies:
– Automatic extraction of skills (from applications)
– Semantic Ranking
– Competency Analysis via
Data Mining
– Relation to E-Learning with
skills
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2. Digitalization &Text Generation via OCR
3. Automatic Skill Extraction using Shallow Parsing
3. Intranet – EmployeeMarketplace
1. Paper-basedApplication
Ontologies/Metadata in Human Resources
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Automatic Generation of Metadata
Via OCR from written documents extracted
Predefined skill ontologywith metadata and lexicon
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Semantic-Driven Intranet Portal (I)
• Requirements:• Develop domain-specific terminology for topics• Automatically generate Yahoo-like structure for this
terminology• Allow to add further, complex structured information
to the terminology• Techniques:
• Ontology Engineering• Discovering of Web Documents via Focused
Crawling• Automatic Classification of Documents into Ontology• Cooperative Metadata Engineering
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Semantic-Driven Intranet Portal (II)
Human ResourceStrategy:
- Define relevant topics in the form of an ontology
- Cooperatively add further information in the form of metadata!
Semantic Portals for HR strategy
- Search relevant Web resources
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Virtual Museum (I)
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Virtual Museum (II)
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News Services - Content Syndication with RSS (I)13.12.2005
NEWSARE FREE!
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News Services - RDF Site Summary RSS (II)
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Content Services - OntoWeb Community Portal
OntoWeb Community
AnnotatedWeb PagesGenerated
Content Objects
Participating Site2
{ }
Participating Siten
{ }
Participating Site1
{ }
...
OntologyBrowse & Query
Front End
ContentSyndication
Service
http://www.ontoweb.org
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General Web Services13.12.2005
• Web services
– perform functions, which can be anything from simple requests to complicated business processes!
– will transform the Web from a collection of information to a distributed device of computation
• Web services clearly require
a semantic-driven description!
=> Semantic Web Enabled
Web Services
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HARMONISE – Interoperability in
Tourism • The tourism industry is
essentially an information business where data interoperability is necessary to create dynamic markets and cooperation.
• Build bridges between different tourism marketplaces via Semantic Web technologies MAPPING
DISCOVERY!• An ontology will mediate
between the different underlying representations.
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Agenda13.12.2005
• Introduction & Motivation
• Introduction - Semantic Web
• Semantic Web Applications
• Semantic Web Technology
– A Layered Approach
– RDF(S)
– KAON Open Source Infrastructure
• Next Steps
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The Semantic Web As By its Inventor
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XML and its relation to the Semantic Web
• „XML only provides an alphabet, not a vocabulary“. [Forrester Report, December 2001]
• The languages french and english use the same alphabet.
=> Can all french people communicate with english people?
• Adopted to the WWW: – XML provides an alphabet and further important means for
validation and modularization! – XML does not offer any possibilities to transport conceptual
content!
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• RDF: Standard for metadata representation– Basis for interoperability in applications– Cost effective development of tools and
applications– Basis for very different users: Digital libraries,
content rating, B2B, etc.
• RDF-Schema: Definition of simple ontologies in the WWW.
• W3C Recommendation RDF is used by different software companies and standardization organisations
RDF – Data Model for the Semantic Web
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• Not the subatomic particle ...KArlsruhe Ontology
• Based on RDF(S), with several extensions, e.g. for typed, multilingual lexical expressions
• Component-based, easily extendable application framework
• Open-Source Tool Suite, supporting
KAON – A RDF-based Software Infrastructure
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KAON Architecture
RDFFiles
P2PRelationalDatabase
RelationalDatabase
NLP Service
Ap
pli
cati
on
s
& S
erv
ice
s
Web Application Framework
HTMLBrowser
Ontology and Metadata Editing
Reverse Engineering
SYNDICATION
KAON PortalPortal Maker
OntoMat App Framework
Focused Crawler
Text Mining Evolution
Legacy Portals
KAON-API
RDF-APIK-EdutellaWrapper
KAON-Server
J2EEMid
dle
war
e NLP-API
QEL-Wrapper
NLP-API
Reasoning Service
DOC-API
Doc-Manag. Service
Dat
aA
nd
Rem
ote
Ser
vice
s
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Ontology Engineering Plugin - SOEP
• …
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Database Reverse Engineering Plugin - REVERSE
• …
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Text Extraction Plugin
• …
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Focused Document/Metadata Crawling Plugin
• …
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Further Plugins 13.12.2005
• Automatic Ontology Extraction Component - TextToOnto
• Ontology-based Document Clustering
• Hierarchical Text classification – Automatic Yahoo generation
• View definition component
• Peer-2-Peer-based document annotation and authoring
(for HTML, PDF, JPEG, GIF)
• Graphical Query Interface based on QEL
• SVG-based visualization
• Versioning component
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KAON Portal13.12.2005
• KAON Portal is a set of tools supporting ontology-based web site management
• It supports web-based presentation of information for users (generated and extracted by other components)
• It also provides means for defining information (cooperatively!)
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Rapid Prototyping a Semantic Portal
KAON EngineeringFrontend
KAON User RapidPrototypFrontend
KAON Backend
KAON Server
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Finally: What is behind ? KAON Server!
• Middleware connects applications with data and network services
• Generic API’s for
– Access to ontologies and metadata
– Access to documents
– Access to language processing tools
– P2P Access
• API‘s are implemented, e.g. by Stanfords RDF-API, by J2EE complient implementation,etc.
ConnectorsJXTA HTTP, IIOP
WebDAVJava API
Security
Authorization AuthenticationEncryption Auditing
Management
Transaction ReplicationNaming Services Storage
Data Access
Query UpdateValidatation Inferencing
External Services
TP Monitors DatabasesInference Engines
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Summarization KAON• KAON is basis for approx. 10
research and industry projects. It is also used by external projects all over the world.
• Open Source Community is growing, currently 35 persons.
• KAON is basis for building knowledge-intensive and semantics-based applications.
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Agenda13.12.2005
• Introduction & Motivation
• Introduction - Semantic Web
• Semantic Web Applications
• Semantic Web Technology
• Next Steps
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Conclusion
• We are on the way to a global information structure, being
based on the World Wide Web and it‘s successor Semantic
Web
• The main vision is: Support machine-processable and
interpretable data to provide a higher degree of automatization
(e.g. Web Services, Query Answering, etc.)
• Standards and tools for ontologies and metadata are ready to
use!
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Next Steps
• Semantic Web technology should be the basis for the
Agricultural Ontology Service (AOS)
• KAON already provides ready-to-run, open-source tools on
which the specific AOS functionalities may be built!
• Rapid prototyping approach is promising:
Convert AGROVOC in RDF(S), connect it with existing data
sources and present the information in the Web browser!
