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McGuinness AAAI July 28, 2002
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
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 thereby limiting needs for human disambiguation input, human
interpretation, multiple answer display, translation assistance, agent assistance, adaptivity support, etc.)
Ontologies
DAML/OWL-enabled web
pages
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 LanguagesRDF/SXML
DAML-ONT
Formal FoundationsDescription Logics
FACT, CLASSIC, DLP, …
Frame Systems
DAML+OIL(OWL)
OIL
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 meta-data efforts. “
• History– W3C Announcement in November 2001 -
http://lists.w3.org/Archives/Public/www-rdf-logic/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 Ontology TranslationBrowser PersistenceCrawler Query ToolsEditor RDMS MappingGraph Visualizer Report GenerationTransformation Search Validator Ontology AnalyzerImporter Ontology EditorInference Engine
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 SemanticsApplied 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.
• 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:
McGuinness AAAI July 28, 2002
CIRCA in Publishing
USERS
USERS
News Content
CIRCA Technology
Auto-Categorizer
Metadata Creator
Page Summarizer
Proprietary Content
Management System
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
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, ontology-enhanced knowledge capture, etc.
• Lets get together…..
McGuinness AAAI July 28, 2002
Extras
McGuinness AAAI July 28, 2002
What is an Ontology?
Catalog/ID
GeneralLogical
constraints
Terms/glossary
Thesauri“narrower
term”relation
Formalis-a
Frames(properties)
Informalis-a
Formalinstance
Value Restrs.
Disjointness, Inverse, part-
of…
McGuinness AAAI July 28, 2002
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
www.ksl.stanford.edu/people/dlm