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Dagstuhl Seminar 02061

Rule Markup Techniques

Harold Boley*, Benjamin Grosof**, Said Tabet***, Gerd Wagner****
*DFKI Kaiserslautern, Germany   **MIT Sloan School of Management, USA   ***Nisus, USA   ****Eindhoven University of Technology, The Netherlands


International Conference and Research Center for Computer Science
Schloss Dagstuhl (Photo Gallery)
D-66687 Wadern, Germany

New Date

Sunday (afternoon), 3rd February 2002 - Friday, 8th February 2002

Motivation and Goals of the Seminar

Rules have classically been used in formal languages, compiler technology, databases, logic programming, knowledge representation, and OO modeling, with applications ranging from car diagnosis, to email filtering, to enterprise integration. Rule markup in the Web has become a hot topic since rules were identified as a Design Issue of the Semantic Web. The Semantic Web is a new W3C Activity trying to represent information in the World Wide Web such that it can be used by machines not just for display purposes, but for automation, integration, and reuse across applications.

Rule markup techniques for the Semantic Web, however, have been less systematically studied than the corresponding vocabulary (taxonomy) markup. This Dagstuhl Seminar  tries to fill the gap by exploring rule systems (e.g., extended Horn logics) suitable for the Web, their (XML and RDF) syntax, semantics, tractability/efficiency, and transformation/compilation. Both derivation rules (which may be evaluated bottom-up as in deductive databases, top-down as in logic programming, or by tabled resolution as in XSB)  and reaction rules (also called "active" or "event-condition-action" rules), as well as any combinations, will be considered.

Ontologies for the Semantic Web can use rules to define axioms operating on a taxonomy, but also to compute the taxonomy from given concept definitions. Further purposes of rule markup include:

To accomodate the various user communities from knowledge-based systems, to intelligent agents, to e-commerce, possibilities for a modular rule-language hierarchy will be discussed. It should permit the mixing and matching of rules of appropriate expressive power as well as computational efficiency for classes of applications. This may be facilitated by a separation of concerns:

Semantics: A classical hierarchy version can be bottomed on ground facts over individual constants; a Webized version could also permit URIs as arguments and names of (binary) relations, much like in RDF triples. On this basis, the classical Datalog, Horn-rule, and equational-logic layers could similarly be extended by URIs as relation, constructor, and function symbols. More advanced rule extensions could include suitable negations for the open world of the Web, feature or F-Logic terms for RDF's anonymous resources, labelings for prioritized business rules, and local rule packages for N3's contexts. The power-efficiency tradeoff should inform us whether the hierarchies, classical and Webized, can be topped by rules in full first-order or even restricted higher-order logic.

Syntax: Classical and Webized rules from the hierarchy can be marked up in pure XML, RDF, or a combination of both, as reflected by the evolution of RuleML. It should be examined where current definition methods (e.g., DTDs vs. XML Schemas) are sufficient for such rule markup and where they would need revisions/extensions. Also non-XML rule(-presentation) formats may be considered for (editors of) a future Web such as colored-ASCII versions of ISO Prolog, Relfun, KIF, Jess, F-Logic, and N3 or graphical notations inspired by XML's trees and RDF's directed labeled graphs.

This Dagstuhl Seminar is thus expected to contribute to some open issues of recent proposals such as Notation 3 (N3), DAML-Rules, and the Rule Markup Language (RuleML). Furthermore, by studying issues of combining rules and taxonomies via sorted logics, description logics, or frame systems, the Seminar will also discuss the US-European proposal DAML+OIL. Two particular issues that will be addressed during this seminar are efficient implementation techniques (e.g., via Java-based rule engines) and major exchange applications (e.g., using e-business rules).

In sum, "Rule Markup Techniques" aims at bringing together the classical- and Web-rule communities to cross-fertilize between their foundations, methods, and applications. The long-term goal is a Web-based standard for rules that makes use of, and is also useful to, the classical rule perspective. Additional Seminar material will be available online from http://www.dfki.de/ruleml/rmt. Seminar participants are encouraged to suggest further steps in this international effort at any time.

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Address Information

Harold Boley
D-67663 Kaiserslautern
Phone: +49-631-205-3459
Fax: +49-631-205-3210
Email: boley@dfki.de
Homepage: http://www.dfki.uni-kl.de/~boley

Benjamin Grosof
MIT Sloan School of Management
Room E53-317
50 Memorial Drive
Cambridge, MA 02142
Phone: (+1 617) 253-8694
Fax: (+1 617)258-7579
Email: bgrosof@mit.edu
Homepage: http://www.mit.edu/~bgrosof/

Said Tabet
Nisus, Inc.
180, Turnpike Road
Westboro, MA 01581
Phone: +1 508 898 2288 extension 16
Fax: +1 508 898 9668
Email: stabet@nisusinc.com
Homepage: http://people.ne.mediaone.net/stabet/

Gerd Wagner
Faculty of Technology Management
Eindhoven University of Technology
P.O. Box 513
5600 MB Eindhoven
The Netherlands
Phone: (+31 40) 247 26 17
Fax: (+31 40) 247 26 12
Email: G.Wagner@tm.tue.nl
Homepage: http://tmitwww.tm.tue.nl/staff/gwagner/

Brief Resumes of the Organizers

Harold Boley

Dr. Harold Boley is a senior researcher at the German Research Center
for Artificial Intelligence (DFKI), where he acts as the W3C Advisory
Committee Representative and leads the EU project Clockwork on
Web-based knowledge management for collaborative engineering.  He is
also a senior lecturer of computer science and mathematics at the
University of Kaiserslautern, where he conceived AI-oriented XML and
RDF courses.  Dr. Boley's focus now is XML-based knowledge markup and
RDF-based Semantic Web techniques.  He was a visiting researcher in
the Knowledge Modeling Group at Stanford University in 1999.  Before
that, he led, and published on, several government and industrial
projects in knowledge representation, compilation, and evolution. He
received PhD and Habilitation degrees in computer science from the
Universities of Hamburg and Kaiserslautern, respectively.  He
developed the Relational-Functional Markup Language (RFML) and,
together with Dr. Said Tabet, launched the Rule Markup Initiative

Benjamin Grosof

Dr. Benjamin Grosof is Assistant Professor in Information Technology at
the MIT Sloan School of Management.  His research addresses e-commerce
and Web technology, combining agent communication, XML, and knowledge
representation for applications in contracting, negotiation, and
business policies.  He co-leads the RuleML initiative, an emerging
industry standard for XML Rules.  He is Principal Investigator
currently for a project in the DARPA Agent Markup Language (DAML)
initiative, designing knowledge-level techniques to realize the vision
of the Semantic Web.  Previously, he was a senior research scientist
at IBM T.J. Watson Research Center.  While at IBM, most recently he
founded and led a project on Business Rules for E-Commerce.  This
produced IBM CommonRules (V2.1 currently on IBM alphaWorks), which
pioneered XML inter-operable business rules with conflict handling and
XML agent communication.  He co-led its application piloting for
rule-based XML agent contracting in EECOMS, a $29Million NIST industry
consortium project on manufacturing supply chain management.  He holds
a PhD from Stanford University in Computer Science, with specialty
Artificial Intelligence, and a BA from Harvard University in Applied
Mathematics, with specialty economics and management science.  He is
author of over 30 refereed publications, two major software releases,
and one patent; and has served on numerous program committees,
including co-chairing the AAAI Conference Workshops on AI in
E-Commerce (1999) and Knowledge-Based E-Markets (2000).  He will
be co-teaching a tutorial on Agent Communication in Knowledge Based
Electronic Markets at the IJCAI-2001 Conference.

Said Tabet

Dr. Said Tabet is the Chief Scientist at Nisus Incorporated, USA,
leading the development of Knowledge Based Personalization products
for both the Wireless and the Wired Web. He also acts as the W3C
Advisory Committee Representative of Nisus. Said Tabet has extensive
experience in research and industry and academia working on Rule-Based
Systems and Artificial Intelligence. Prior to joining Nisus, he was a
Principal Knowledge Engineer at Brightware/MindBox, where he developed
and deployed several key Knowledge Based systems for decision support
in such verticals as Financial Services and Telecommunications using
ART*Enterprise and XML, Case Based Reasoning and distributed systems
technologies. He is currently focused on XML-Based Knowledge
Representation and Management, Semantic Web, AI for Mobile and
Wireless Internet. In 1998, he received recognition for outstanding
contribution to Inference/Brightware. He completed his Masters and PhD
from the University of Grenoble and conducted additional research at
Brandeis University. He is a member of the American Association for
Artificial Intelligence and serves as a Program Committee member on
various AI conferences and workshops (IJCAI, PRICAI). Together with
Dr. Harold Boley, he launched the Rule Markup Initiative (RuleML).

Gerd Wagner

Dr. Gerd Wagner is an Assistant Professor at the Faculty of Technology
Management, Eindhoven University of Technology. He received an MSc
in mathematics and a PhD in philosophy from the Free University of Berlin,
and a German Habilitation degree in computer science from the University
of Leipzig. He was visiting researcher at the Institute de Recherche en
Informatique de Toulouse in 1994 and at Universidade Nova de Lisboa
in 1995. His reasearch interests are focused on the foundations of
information and knowledge systems and of multiagent systems.
Dr. Wagner has been the guest editor of a 1997 special issue of the
Journal of Applied Nonclassical Logic on "Handling Inconsistency in
Knowledge Systems", and the author of the book "Foundations of
Knowledge Systems with Applications to Databases and Agents"
(Kluwer, 1998). In 1999, he initiated and co-organized the first
International Workshop on Agent-Oriented Information Systems
(AOIS) which has then been established as an annual workshop series.

List of Researchers for Invitation as Participants