The Semantic Web
(State of the art and
implications for language
processing)
Deborah McGuinness
Associate Director and Senior Research Scientist
Knowledge Systems Laboratory
Stanford University
Stanford, CA USA
[email protected]
http://www.ksl.stanford.edu/people/dlm
McGuinness
AAAI July 28, 2002
Outline
• Vision of the web today and tomorrow
• The key to tomorrow’s web is semantics
• Semantics on the web requires:
– Language for encoding meaning (DAML+OIL, OWL)
– Ontologies
– Tools
• Conclusion and Pointers
McGuinness
AAAI July 28, 2002
Today: Rich Information Source for
Human Manipulation/Interpretation
Human
Human
McGuinness
AAAI July 28, 2002
“I know what was input”
• Global documents and terms indexed and available for search
• Search engine interfaces
• Entire documents retrieved according to relevance (instead of
answers)
• Human input, review, assimilation, integration, action, etc.
• Special purpose interfaces required for user friendly applications
The web knows what was input but does little interpretation,
manipulation, integration, and action.
Analogous to a new assistant who is thorough yet lacks common
sense, context, and adaptability
McGuinness
AAAI July 28, 2002
Tomorrow: Rich Information Source
for Agent Manipulation/Interpretation
Human
Agent
Agent
McGuinness
AAAI July 28, 2002
“I know what was meant”
•
•
•
•
•
Understand term meaning and user background
Interoperable (can translate between applications)
Programmable (thus agent operational)
Explainable (thus maintains context and can adapt)
Capable of filtering (thus limiting display and
human intervention requirements)
• Capable of executing services
McGuinness
AAAI July 28, 2002
Layer Cake Foundation
McGuinness
AAAI July 28, 2002
Stated goals of Semantic Web
• Define conventions for applications that exchange metadata on the
Web
•
•
Enable vocabulary semantics to be defined by communities of
expertise, not W3C
Provide for the fine-grained mixing of diverse metadata
•
Making it cost-effective for people to effectively record their
knowledge.
•
Ultimate goal - the design of enabling technologies to support
machine facilitated global knowledge exchange
McGuinness
AAAI July 28, 2002
Semantic Markup
Languages such as OWL, DAML+OIL
(http://www.w3.org/2001/sw/WebOnt/,
http://www.daml.org)
• Encoding background info
• User modeling info
• Annotating web pages
• Annotating services
Ontologies
DAML/OWLenabled web
pages
thereby limiting needs for human disambiguation input, human
interpretation, multiple answer display, translation assistance,
agent assistance, adaptivity support, etc.)
McGuinness
AAAI July 28, 2002
XML
• World Wide Web Consortium (W3C) standard
• Provides important solution to syntax problem and
simple semantics and schemas:
<SSN>555-17-1234</SSN>
• Now we can describe the meaning of words
• Many applications of XML appearing:
– Geographic Markup Language (GML)
– Extensible rights Markup Language (XrML)
– Chemical Markup Language (CML)
Problem: Limited semantics, limited ontology creation
McGuinness
AAAI July 28, 2002
DARPA Agent Markup Language
•
•
•
•
http://www.daml.org/about.html
Extends the vocabulary of XML and RDF/S
Provides rich ontology representation language
Language features chosen so language may have
efficient implementations
McGuinness
AAAI July 28, 2002
DARPA DAML Program
• Began in August 2000 Kickoff meeting
• 19 Research groups supported
• Initial ontology language aims to extend
XML, RDF/S, benefit from frames, benefit
from principled KR systems like
Description Logics
• DAML-ONT released in Oct. 2000
• DAML+OIL released in March 2001
McGuinness
AAAI July 28, 2002
DAML Language
Web Languages
RDF/S
XML
DAML-ONT
DAML+OIL
(OWL)
Frame Systems
OIL
Formal Foundations
Description Logics
FACT, CLASSIC, DLP, …
McGuinness
AAAI July 28, 2002
DAML+OIL -> W3C
• W3C Webont working group formed with
DAML+OIL submission as starting point
http://www.w3.org/Submission/2001/12/
McGuinness
AAAI July 28, 2002
W3C Web Ontology Working Group
• Web Ontology Working Group in the W3C
Semantic Web Activity aimed at “extending the
semantic reach of current XML and RDF metadata efforts. “
• History
– W3C Announcement in November 2001 http://lists.w3.org/Archives/Public/www-rdflogic/2001Nov/0000.html
– Weekly teleconferences starting in November 2001
McGuinness
AAAI July 28, 2002
WEBONT catches on….
• Includes over 50 members from over 30 organizations.
– Industry including:
• Large companies such as Daimler Chrysler, EDS, Fujitsu, HP, IBM, Intel,
Lucent, Nokia, Philips Electronics, Sun, Unisys, …
• Newer/smaller companies such as IVIS Group, Network Inference, Stilo
Technology, Unicorn Solutions, …
– Government and Not-For-Profits:
• Defense Information Systems Agency, Interoperability Technology
Association for Information Processing, Japan (INTAP) , Intelink Mgt Office,
Mitre, …
– Universities and Research Centers:
• University of Bristol, University of Maryland, University of Southamptom,
Stanford University, …
• DFKI (German Research Center for Artificial Intelligence),
Forschungszentrum Informatik
– Invited Experts
• Well-known academics from non-W3C members
McGuinness
AAAI July 28, 2002
WEBONT cont.
• Quarterly Face to Face meetings in
–
–
–
–
Murray Hill: http://www.w3.org/2001/sw/WebOnt/ftf1.html
Amsterdam: http://www.w3.org/2001/sw/WebOnt/ftf2.html
Stanford: http://www.w3.org/2001/sw/WebOnt/ftf3.html
Upcoming – Bristol, and xxx
• Interesting Documents:
– DAML+OIL submission – full spec with reference description,
walkthrough, FOL and model theoretic semantics,
http://www.w3.org/TR/daml+oil-reference
– Use Case and requirements document:
http://www.w3.org/TR/webont-req/
McGuinness
AAAI July 28, 2002
OWL Lite and OWL
• Feature Synopsis:
http://www.w3.org/TR/owl-features/
• Reference Description:
http://www.w3.org/TR/owl-ref/
• Abstract Syntax:
http://www.w3.org/TR/owl-absyn/
McGuinness
AAAI July 28, 2002
OWL Lite Features
•
RDF Schema Features
– Class
– rdf:Property
– rdfs:subClassOf
– rdfs:subPropertyOf
– rdfs:domain
– rdfs:range
– Individual
•
Equality and Inequality
– sameClassAs
– samePropertyAs
– sameIndividualAs
– differentIndividualFrom
•
Restricted Cardinality
– minCardinality (restricted to 0 or 1)
– maxCardinality (restricted to 0 or 1)
– cardinality (restricted to 0 or 1)
McGuinness
AAAI July 28, 2002
OWL Lite Features (cont)
•
•
•
Property Characteristics
– inverseOf
– TransitiveProperty
– SymmetricProperty
– FunctionalProperty(unique)
– InverseFunctionalProperty (unambiguous)
– allValuesFrom (universal local range restrictions; previously toClass)
– someValuesFrom (existential local range restrictions; previously
hasClass)
Datatypes
– Following the decisions of RDF Core.
Header Information
– imports
– Dublin Core Metadata
– versionInfo
McGuinness
AAAI July 28, 2002
OWL Features
•
Class Axioms
–
–
–
–
•
oneOf (enumerated classes)
disjointWith
sameClassAs applied to class expressions
rdfs:subClassOf applied to class expressions
Boolean Combinations of Class Expressions
– unionOf
– intersectionOf
– complementOf
•
Arbitrary Cardinality
– minCardinality
– maxCardinality
– cardinality
•
Filler Information
– hasValue Descriptions can include specific value information
McGuinness
AAAI July 28, 2002
Tools
In order to take off, we need tools: http://www.daml.org/tools/
Annotation
Browser
Crawler
Editor
Graph Visualizer
Transformation
Validator
Importer
Inference Engine
Ontology Translation
Persistence
Query Tools
RDMS Mapping
Report Generation
Search
Ontology Analyzer
Ontology Editor
Many are in research labs, but some in companies…
Network Inference, Sandpiper, Ontoprise, ….
McGuinness
AAAI July 28, 2002
Ontologies Exploding
• Upper Level Ontologies Emerging:
– UNSPSC, SUO, OpenCyc, OpenDirectory,
TAP, …
• Specialized Ontologies Emerging
– UMLS, NPC,
• Libraries
– http://www.daml.org/ontologies/
– http://www.ksl.stanford.edu/ontolingua
McGuinness
AAAI July 28, 2002
Some Observations…
• Markup Languages are growing in
acceptance and expressive power
• User base, tool base, ontology base growing
• Ontology-enhanced applications springing
up (not just in ivory towers like FindUR,
eCyc, …)
McGuinness
AAAI July 28, 2002
Simple Ontology-Enhanced Apps
McGuinness
AAAI July 28, 2002
McGuinness
AAAI July 28, 2002
Applied Semantics
Applied Semantics uses a large scale ontology, or knowledge base
of concepts and their relationships, to bring semantic understanding
to the processing of unstructured information. Our software products
and services improve the business processes for publishing,
enterprise applications, and internet infrastructure markets by
automating content tagging, categorization, and summarization for
more effective information sharing and retrieval.
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McGuinness
Founded in 1998
Won Internet World Fall 1999 “Best of Show” for meaning-based search
40 employees
Funding from: Zero Gravity, Ridgestone, others
50+ customers, including:
AAAI July 28, 2002
CIRCA in Publishing
CIRCA
Technology
AutoCategorizer
News Content
Metadata
Creator
Proprietary
Content
Management
System
Page
Summarizer
A major newspaper uses Auto-Categorizer by IPTC code (standard
publishing taxonomy), Metadata Creator to generate meaningful thematic
keywords, and Page Summarizer to summaries of varying lengths.
McGuinness
AAAI July 28, 2002
U
S
E
R
S
Conclusion/Discussion
• The Semantic Web is in its infancy today
but is ready for applications
• Markup Language, Ontologies, and some
tools are ready for use
• Hybrid applications may be the first to grow
like ontology-enhanced search, ontologyenhanced knowledge capture, etc.
• Lets get together…..
McGuinness
AAAI July 28, 2002
Extras
McGuinness
AAAI July 28, 2002
What is an Ontology?
Catalog/
ID
Thesauri
“narrower
term”
relation
Terms/
glossary
McGuinness
Frames General
Formal
is-a (properties) Logical
constraints
Informal
is-a
Formal
instance
AAAI July 28, 2002
Disjointness,
Value Inverse, partRestrs. of…
Some Pointers
• Ontologies Come of Age Paper:
http://www.ksl.stanford.edu/people/dlm/papers/
ontologies-come-of-age-abstract.html
• OWL: http://www.w3.org/TR/owl-features/ ,
http://www.w3.org/TR/owl-ref/
• DAML+OIL: http://www.daml.org/ ,
http://www.w3.org/TR/daml+oil-reference
McGuinness
AAAI July 28, 2002
Contact Information
[email protected]
www.ksl.stanford.edu/people/dlm
McGuinness
AAAI July 28, 2002
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The Future of the Web