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W3C Tracking OWL

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Title: W3C Tracking OWL


1
W3C Tracking OWL
  • David De Roure
  • GGF Semantic Grid Research Group
  • www.semanticgrid.org/GGF

2
XMLRDF Basics
  • URI - Uniform Resource Identifier
  • XML - eXtensible Markup Language
  • XML Namespaces
  • XML Schema
  • RDF - Resource Description Framework
  • RDF Schema

3
Resource Description Framework
4
Not Rocket Science
Is this rocket science? Well, not really. The
Semantic Web, like the World Wide Web, is just
taking well established ideas, and making them
work interoperability over the Internet. This is
done with standards, which is what the World Wide
Web Consortium is all about. We are not inventing
relational models for data, or query systems or
rule-based systems. We are just webizing them. We
are just allowing them to work together in a
decentralized system - without a human having to
custom handcraft every connection. -- Tim
Berners-Lee, Business Case for the Semantic Web,
http//www.w3.org/DesignIssues/Business
5
Jargon interop
  • In science, models provide interoperability
    across jargons
  • Mathematical models equations of a system
  • Physical models sticks and balls of the atom
  • Virtual models the visualization of a complex
    data set
  • INFORMATION MODELS taxonomies and thesauri

6
Ontologies
  • Ontologies extend thesaurus information models to
    provide
  • Semantic restrictions on property relations
  • Must have vs. May have vs. Doesnt have
  • Has some vs. has N vs. has 1
  • Some vs. All property restrictions
  • Formal underpinnings
  • Note rules, logics, proofs are parts of
    ontologies, but not yet at a consensus level
    for standardization

7
RDFS
  • The Resource Description Framework (RDF) was the
    first language specified by the W3C for
    representing semantic information about arbitrary
    resources.
  • RDF Schema (RDFS) is a W3C candidate
    recommendation for an extension to RDF to
    describe RDF vocabularies.
  • RDFS can be used to create ontologies, but it is
    purposefully lightweight, with less expressive
    power than OWL.

8
Other ontology efforts
  • DAML - DARPA Agent Markup Language
  • DAML-ONT
  • MCF - Meta Content Framework.
  • Ontobroker
  • On-To-Knowledge
  • OIL - Ontology Inference Layer
  • SHOE - Simple HTML Ontology Extensions
  • XOL

9
DAMLOIL
  • Researchers, including many of the main
    participants in both the OIL and DAML-ONT
    efforts, got together in the Joint US/EU ad hoc
    Agent Markup Language Committee to create a new
    web ontology language
  • This language DAMLOIL built on both OIL and
    DAML-ONT, was submitted to the W3C as a proposed
    basis for OWL, and was subsequently selected as
    the starting point for OWL

10
DAMLOIL uptake
  • DAMLOIL is already the most used ontology
    language in history
  • Sept 30, 02 Crawler finds 5M DAML statements on
    20,000 web pages
  • Doesnt include many instance KBs tied to
    ontologies
  • Doesnt include many very large RDFS-based KBs
    that include some OWL
  • OWL is being supported by large corporation labs
  • Web tool developers IBM, HP, Sun, Intel, Fujitsu
  • Content providers Daimler-Chrysler, Nokia,
    Motorola, EDS, Agfa
  • OWL is starting to be used by thesaurus
    distributors
  • C.f. National Cancer Institute metathesaurus to
    be released in OWL

11
OWL Web Ontology Language
12
OWL Extends RDF
  • RDF-schema
  • Class, subclass
  • Property, subproperty
  • Restrictions
  • Range, domain
  • Local, global
  • Existential
  • Cardinality

Combinators Union, Intersection Complement Symme
tric, transitive Mapping Equivalence Inverse
13
OWL is not
  • OWL is not a knowledge representation language
    per se
  • Definitely not The standard for KR
  • OWL is not a Description Logic per se
  • It does support DL idioms
  • E.g. Lymphoma is restricted to be a subClassOf
    those things whose disease property is Cancer
  • It includes a subset which is complete, and
    decidable
  • But, it will allow uses that DLs do not

14
OWL Documents
  • Web Ontology Language (OWL) Guide Version 1.0,
    W3C Working Draft, 26 February 2003
  • Requirements for a Web Ontology Language. W3C
    Working Draft, 08 July 2002.
  • Feature Synopsis for OWL Lite and OWL. Deborah L.
    McGuinness and Frank van Harmelen. W3C Working
    Draft, 29 Jul 2002.
  • OWL Web Ontology Language 1.0 Reference. Mike
    Dean and Guus Schreiber. W3C Working Draft, 3
    February 2003.
  • OWL Web Ontology Language 1.0 Abstract Syntax.
    Peter F. Patel-Schneider, Ian Horrocks, and Frank
    van Harmelen. W3C Working Draft 29 July 2002.
  • Model-Theoretic Semantics for OWL, Peter F.
    Patel-Schneider, Partick Hayes, and Ian Horrocks.
    3 February 2003

15
OWL Guide
  • This document demonstrates the use of the OWL
    language to
  • formalize a domain by defining classes and
    properties of those classes,
  • define individuals and assert properties about
    them, and
  • reason about these classes and individuals to the
    degree permitted by the formal semantics of the
    OWL language.

16
The Species of OWL
  • OWL Lite supports those users primarily needing a
    classification hierarchy and simple constraint
    features. It should be simpler to provide tool
    support for OWL Lite than its more expressive
    relatives, and provides a quick migration path
    for thesauri and other taxonomies.

17
The Species of OWL
  • OWL DL supports those users who want the maximum
    expressiveness without losing computational
    completeness and decidability of reasoning
    systems. OWL DL was designed to support the
    existing Description Logic business segment.

18
The Species of OWL
  • OWL Full is meant for users who want maximum
    expressiveness and the syntactic freedom of RDF
    with no computational guarantees. It allows an
    ontology to augment the meaning of the
    pre-defined (RDF or OWL) vocabulary.

19
Expressiveness
  • OWL Lite supports cardinality constraints, but it
    only permits cardinality values of 0 or 1.
  • In OWL DL, a class cannot also be an individual
    or property, a property can not also be an
    individual or class.
  • In OWL Full a class can be treated simultaneously
    as a collection of individuals and as an
    individual in its own right.

20
See some OWL!
  • Fragments from the Wine Ontology example in the
    OWL Guide

21
Namespaces
  • ltrdfRDF xmlns http//www.example.org/wine
  • xmlnsvin http//www.example.org/wine
  • xmlnsfoodhttp//www.example.org/food
  • xmlnsowl "http//www.w3.org/2002/07/owl"
  • xmlnsrdf http//www.w3.org/1999/02/22-rdf-synta
    x-ns
  • xmlnsrdfshttp//www.w3.org/2000/01/rdf-schema
  • xmlnsxsd "http//www.w3.org/2000/10/XMLSchema"
    gt

22
Ontology header
  • ltowlOntology rdfabout"http//www.example.org/wi
    ne"gt
  • ltrdfscommentgtAn example OWL ontologylt/rdfscomm
    entgt
  • ltowlpriorVersion rdfresource"http//www.exampl
    e.org/wine-2102.owl"/gt
  • ltowlimports rdfresource"http//www.example.org
    /food.owl"/gt
  • ltrdfslabelgtWine Ontologylt/rdfslabelgt
  • ...
  • lt/owlOntologygt

23
Simple classes
  • ltowlClass rdfID"Winery"/gt
  • ltowlClass rdfID"Region"/gt
  • ltowlClass rdfID"ConsumableThing"/gt
  • ltowlClass rdfID"Wine"gt
  • ltrdfssubClassOf rdfresource"foodPotableLiqui
    d"/gt
  • ltrdfslabel xmllang"en"gtwinelt/rdfslabelgt
  • ltrdfslabel xmllang"fr"gtvinlt/rdfslabelgt
  • ...
  • lt/owlClassgt

24
Tools
  • Being able to express ontologies is not enoughwe
    need tools!
  • Existing tools, especially DAMLOIL, are adapting
    to OWL
  • Available for use in the lifetime of this group

25
(No Transcript)
26
Conclusions
  • OWL is more expressive than RDF(S)
  • OWL evolved from DAMLOIL
  • There are three species of OWL
  • OWL nearing completion and documents are
    available
  • See OWL Guide for examples
  • Tools are increasingly available

27
Acknowledgements
  • These slides are primarily based on the OWL Guide
    and on a presentation by Jim Hender
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