Approximate Reasoning for the Semantic Web

Advanced Course at ESSLLI 2006, Malaga, Spain, August 2006

Frank van Harmelen, Pascal Hitzler and Holger Wache


Expressive logical knowledge representation and reasoning tasks are of high computational complexity and therefore scale badly to large knowledge bases. Since expressive reasoning is a necessity for advanced artificial intelligence applications, theoreticians and practitioners are therefore faced with a scalability problem of fundamental nature.

Approximate reasoning allows to deal with time-critical reasoning systems in a controlled and logically sound fashion. It is based on controlled alterations of the inference relation in order to achieve lower reasoning complexities. Consequently, the resulting systems are much more efficient, but at the price of unsoundness or incompleteness, but in a well-understood manner which allows to arrive at correctness estimates, or at algorithms which subsequently correct initially given answers if more time is available.

Contents: Overview

We will start with an introduction to the semantic web and corresponding knowledge representation formalisms, and in particular to the Web Ontology Language OWL. Then we will review the fundamental approaches to approximate reasoning, and finally focus on recent results concerning ontological knowledge bases as studied in the context of the Semantic Web.

Contents: Preliminary Schedule

Course Material

the Semantic Web: Web of (integrated) Data
Semantic Web Languages: RDF, RDF Schema, OWL
Why the Semantic Web needs approximate reasoning
OWL Semantics and Tableau Reasoning
Approximate reasoning in general
Approximate reasoning on tableaux
Approximate Resolution for OWL

Presenters Information

Prof. Frank van Harmelen is professor of Knowledge Representation and Reasoning in the AI department (Faculty of Science) at the Vrije Universiteit Amsterdam. He studied mathematics and computer science in Amsterdam. In 1989, he was awarded a PhD from the Department of AI in Edinburgh for his research on meta-level reasoning. After his PhD research, he moved back to Amsterdam where he was involved in the REFLECT project on the use of reflection in expert systems, and in the KADS project, where he contributed to the development of the (ML)2 language for formally specifying Knowledge-Based Systems. In 1995 he joined the AI research group at the Vrije Universiteit Amsterdam, where he is heading the Knowledge Representation and Reasoning group. He was an active member of the W3C working group which designed the Web Ontology Language OWL, and has published the first textbook on the Semantic Web. He is author of a number of books, and has published over 75 research papers.
Dr. habil. Pascal Hitzler is assistant professor at the Institute for Applied Informatics and Formal Description Methods (AIFB) at the University of Karlsruhe in Germany, where he is involved in national and international projects on semantic web technologies, including KnowledgeWeb, SEKT, NeOn and SmartWeb. Before this, he was a postdoctoral researcher at the Artificial Intelligence Institute at Dresden University. He received a PhD in Mathematics from UCC Cork, Ireland in 2001, and a Diplom in Mathematics and Computer Science from the University of Tübingen, Germany, in 1998. His research record lists over 80 publications in such diverse areas as neural-symbolic integration, semantic web, knowledge representation and reasoning, lattice and domain theory, denotational semantics, and set-theoretic topology. He is a lecturer at the Semantic Web Academy Karlsruhe. He serves as a reviewer for international journals, conferences, and research project applications. He has also been an organizer of international enhancement programmes for highly skilled students in Mathematics and Computer Science, and has served as an editor for several books in this area.
Dr. Holger Wache is project leader and senior research assistant in the department of artificial intelligence at the Vrije Universiteit Amsterdam in The Netherlands. He is work package leader in KnowledgeWeb, a network of excellence funded by the European Union. For the European Semantic Web Conference 2006 he is resposnible for the Poster and Demo session. Holger Wache published in diverse areas like knowledge representation and reasoning, description logics and integration of heterogeneous information sources. He was co-organizer of the Workshops on Intelligent Information Integration I and II at KI1997 respectively ECAI-98, of the First International Workshop on Applied Artificial Intelligence and Logistics at KI2004, and of the Workshop on Contexts and Ontologies at AAAI-05. He serves as a reviewer for international journals, conferences, and workshops including the European and International Semantic Web Conferences and the Semantic Web Journal. He was guest editor of two special issues in international journals.