the semantic web (current state and directions)

McGuinness NSF/NCAR October 30, 2002

The Semantic Web (Current State and Directions)

Deborah McGuinness

Associate Director and Senior Research Scientist

Knowledge Systems Laboratory

Stanford University

Stanford, CA USA

dlm@ksl.stanford.edu

http://www.ksl.stanford.edu/people/dlm

McGuinness NSF/NCAR October 30, 2002

Outline

• Web: today and tomorrow– The key to tomorrow’s web is semantics

• Semantics on the web requires:– Language for encoding meaning (XML, RDF/S ->

DAML+OIL, OWL)

– Ontologies (Term descriptions and their interrelationships)

– Tools

• Conclusion and Pointers

McGuinness NSF/NCAR October 30, 2002

Today: Rich Information Source for Human Manipulation/Interpretation

Human

Human

Human

Human

McGuinness NSF/NCAR October 30, 2002

“I know what was input”

The web knows what text was input (and is great at information dissemination) but does little interpretation, manipulation, integration, and action.

Analogous to a new assistant who is thorough yet lacks common sense, context, adaptability, and the ability to interpret for you

McGuinness NSF/NCAR October 30, 2002

Tomorrow: Rich Information Source for Agent Manipulation/Interpretation

Human

Agent

Agent

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“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 NSF/NCAR October 30, 2002

Layer Cake Foundation

McGuinness NSF/NCAR October 30, 2002

Semantic Markup In languages such as OWL, DAML+OIL(http://www.w3.org/2001/sw/WebOnt/, http://www.daml.org), we capture• Background info• User modeling infofor• Annotating web pages (man/automatically)• 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 NSF/NCAR October 30, 2002

DAML/OWL Language

Web LanguagesRDF/SXML

DAML-ONT

Formal FoundationsDescription Logics

FACT, CLASSIC, DLP, …

Frame Systems

DAML+OILOWL

OIL

•Extends vocabulary of XML and RDF/S•Rich ontology representation language•Language features chosen for efficient implementations

McGuinness NSF/NCAR October 30, 2002

W3C WEBONT catches on…. • Includes over 50 members from over 30 international organizations.

– Industry including:• Large companies such as Daimler Chrysler, EDS, Fujitsu, HP, IBM, Intel,

Lucent, Motorola, 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,

• ARDA, CIA, DARPA, DIA, NCI, NIH, NIST, NSF, …– Universities and Research Centers:

• Stanford University, University of Bristol, University of Maryland, University of Southamptom, …

• DFKI (German Research Center for Artificial Intelligence), Forschungszentrum Informatik

– Invited Experts • Well-known academics from non-W3C members

McGuinness NSF/NCAR October 30, 2002

OWL Lite Features • RDF Schema Features

– Class, rdfs:subClassOf , Individual – rdf:Property, rdfs:subPropertyOf – rdfs:domain , rdfs:range

• Equality and Inequality– sameClassAs , samePropertyAs , sameIndividualAs – differentIndividualFrom

• Restricted Cardinality – minCardinality, maxCardinality (restricted to 0 or 1) – cardinality (restricted to 0 or 1)

• Property Characteristics– inverseOf , TransitiveProperty , SymmetricProperty – FunctionalProperty(unique) , InverseFunctionalProperty– allValuesFrom, someValuesFrom (universal and existential local range

restrictions)• Datatypes

– Following the decisions of RDF Core. • Header Information

– imports , Dublin Core Metadata , versionInfo

McGuinness NSF/NCAR October 30, 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 NSF/NCAR October 30, 2002

OWL Lite and OWL

• Feature Synopsis:

http://www.w3.org/TR/owl-features/• Guide:

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 NSF/NCAR October 30, 2002

Do I have to build the ontologies myself? Maybe not….Ontologies (suitable for reuse) are exploding

• Upper Level Ontologies– UNSPSC, SUO, OpenCyc, OpenDirectory, TAP, …

• Specialized Ontologies– UMLS, SNOMED, GO, CIA World Fact book, DAML-S…, even

vc’s – Vulcan,…

• Ontology Libraries– http://www.daml.org/ontologies/– http://www.ksl.stanford.edu/ontolingua

• “Advisory” bodies– Semantic Web Science Foundation, NIST, Ontology.org, …

McGuinness NSF/NCAR October 30, 2002

Ontologies in most areas … including the environment

Quick web search yielded:• Semantic Web for Earth and Environmental Terminology –JPL.

http://oceanesip.jpl.nasa.gov/sweet

• National Institute for environmental eScience – Cambridge - http://www.niees.ac.uk/

• Gene Ontology – “dynamic controlled vocabulary that can be applied

to all organisms” http://www.geneontology.org/

• Design and Creation of Ontologies for Environmental Information Retrieval- Telecordia - http://sern.ucalgary.ca/KSI/KAW/KAW99/papers/Kashyap1/kashyap.pdf

• Ontologies of environmental applications for a digital library of scientific collections - http://dlforum.external.forth.gr:8080/papers/EnviroInfo.pdf

• Waste water ontology – decision support for wastewater treatment processes - http://citeseer.nj.nec.com/ceccaroni00wawo.html

• ... Many others …

McGuinness NSF/NCAR October 30, 2002

Tools

Tools developing: http://www.daml.org/tools/

Annotation Ontology TranslationBrowser PersistenceCrawler Query ToolsEditor RDMS MappingGraph Visualizer Report GenerationTransformation Search Validator Ontology AnalyzerImporter Ontology EditorInference Engine Merging

Many are in research labs, but companies emerging and lasting…Network Inference, Sandpiper, Ontoprise, AppliedSemantics, Sentius, ….

McGuinness NSF/NCAR October 30, 2002

Conclusion/Discussion• The Semantic Web is in its infancy today but is ready for

applications• Markup languages, ontologies, and some tools are ready

for use• Specialized tools are buildable/usable today• Semantic web can be leveraged to support: (items from

Tim, Margaret, Dan, David’s presentations):interoperability, modeling, synthesis, integrity checking, prediction,

information dissemination, quick start to “poor man’s managed/curated data repositories”, foundation for “richer man’s repository, foundation for new communication mode, distributed collaboration, knowledge mgmt, knowledge from data, “democratizing information”, “build between”, …

• Input welcome: if you need something from the semantic web community you don’t see, tell us

McGuinness NSF/NCAR October 30, 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 NSF/NCAR October 30, 2002

Extras

McGuinness NSF/NCAR October 30, 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 NSF/NCAR October 30, 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 or other standards bodies

• 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 NSF/NCAR October 30, 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 NSF/NCAR October 30, 2002

DAML+OIL -> W3C

• W3C Webont working group formed with DAML+OIL submission as starting point http://www.w3.org/Submission/2001/12/

• Web Ontology Working Group in the W3C Semantic Web Activity aimed at “extending the semantic reach of current XML and RDF meta-data efforts. “

McGuinness NSF/NCAR October 30, 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

– Bristol: http://www.w3.org/2001/sw/WebOnt/ftf4– Expected recommendation status at w3c meeting in march.

• 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 NSF/NCAR October 30, 2002

Contact Information

dlm@ksl.stanford.edu

www.ksl.stanford.edu/people/dlm

McGuinness NSF/NCAR October 30, 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 NSF/NCAR October 30, 2002

Simple Ontology-Enhanced Apps

McGuinness NSF/NCAR October 30, 2002