W3C Tracking – OWL - Liacs

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Oct 22, 2013 (3 years and 9 months ago)

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W3C Tracking


OWL

David De Roure

GGF Semantic Grid Research Group

www.semanticgrid.org/GGF


GGF7 Tokyo March 2004

2

XML+RDF Basics


URI
-

Uniform Resource Identifier


XML
-

eXtensible Markup Language


XML Namespaces


XML Schema


RDF
-

Resource Description
Framework


RDF Schema

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Resource Description Framework

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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

GGF7 Tokyo March 2004

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

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Ontologies


Ontologies extend thesaurus
information models to provide


Semantic restrictions on property relations


Must have vs. May have vs. Doesn’t 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

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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.



GGF7 Tokyo March 2004

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

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DAML+OIL


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 DAML+OIL 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



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10

DAML+OIL uptake


DAML+OIL is already the most used ontology
language in history


Sept 30, 02: Crawler finds 5M+ DAML statements
on 20,000+ web pages


Doesn’t include many instance KBs tied to ontologies


Doesn’t 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


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OWL Web Ontology Language

OWL

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OWL Extends RDF


RDF
-
schema


Class, subclass


Property,
subproperty

+ Restrictions


Range, domain


Local, global


Existential


Cardinality

+ Combinators

Union, Intersection

Complement

Symmetric, transitive

+ Mapping

Equivalence

Inverse

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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

GGF7 Tokyo March 2004

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

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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.

GGF7 Tokyo March 2004

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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.


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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.

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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.


GGF7 Tokyo March 2004

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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.

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See some OWL!


Fragments from the Wine Ontology
example in the OWL Guide…

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Namespaces

<rdf:RDF xmlns =http://www.example.org/wine#


xmlns:vin =http://www.example.org/wine#


xmlns:food=http://www.example.org/food#


xmlns:owl ="http://www.w3.org/2002/07/owl#"


xmlns:rdf =http://www.w3.org/1999/02/22
-
rdf
-
syntax
-
ns#


xmlns:rdfs=http://www.w3.org/2000/01/rdf
-
schema#


xmlns:xsd ="http://www.w3.org/2000/10/XMLSchema#">

GGF7 Tokyo March 2004

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Ontology header

<owl:Ontology rdf:about="http://www.example.org/wine">



<rdfs:comment>An example OWL ontology</rdfs:comment>


<owl:priorVersion rdf:resource="http://www.example.org/wine
-
2102.owl"/>


<owl:imports rdf:resource="http://www.example.org/food.owl"/>


<rdfs:label>Wine Ontology</rdfs:label>

...

</owl:Ontology>

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Simple classes

<owl:Class rdf:ID="Winery"/>

<owl:Class rdf:ID="Region"/>

<owl:Class rdf:ID="ConsumableThing"/>


<owl:Class rdf:ID="Wine">


<rdfs:subClassOf rdf:resource="&food;PotableLiquid"/>



<rdfs:label xml:lang="en">wine</rdfs:label>


<rdfs:label xml:lang="fr">vin</rdfs:label>



...

</owl:Class>

GGF7 Tokyo March 2004

24

Tools


Being able to express ontologies is
not enough…we need tools!


Existing tools, especially
DAML+OIL, are adapting to OWL


Available for use in the lifetime of
this group

GGF7 Tokyo March 2004

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Conclusions


OWL is more expressive than
RDF(S)


OWL evolved from DAML+OIL


There are three species of OWL


OWL nearing completion and
documents are available


See OWL Guide for examples


Tools are increasingly available

GGF7 Tokyo March 2004

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Acknowledgements

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