Chair and Memberships

Member of approximately 70 program committees of which a brief selection is provided here:
- Intern. Joint Conference on Artificial Intelligence 2001 (IJCAI'01).
- Constraint Programming (CP'01), Cyprus, 2001.
- 16th American National Conference on Artificial Intelligence (AAAI'98), 1998.
- ACM SIGMOD Symposium on Principles of Database Systems (PODS), 1998.
- European Conference on Artificial Intelligence (ECAI), 1996.
- Intl. Symposium on Knowledge Representation and Reasoning (KR) 1994, 1998.
- Intern. Colloquium on Automata, Languages and Programming (ICALP), 1997.
- Intern. Conference on Computational Complexity , (CCC) 1997 (Former name: Structure in Complexity Theory)
- IEEE Symp. on Logic in Computer Science, (LICS) 1996.
- ACM SIGMOD Symposium on Principles of Database Systems (PODS), 1994.
- International Conference on Data Engineering, 1987, 1988, 1989, 1991.
- International Conference on Extending Database Technology (EDBT), 1988, 1992 (Org. Chairman).
- International Conference on Very Large Data Bases (VLDB) 1989, 1990, 1995.
- International Conference on Deductive and Object-Oriented Databases (DOOD91), 1991, 1994.
- Symposium on Mathematical Fundamentals of Database and Knowledge Base Systems (MFDBS), 1991.
Membership of scientific advisory boards.
Since 1997 head of the LPNMR Steering Committee. LPNMR is is an association organizing world wide scientific activities on logic programming and nonmonotonic reasoning (former head: Prof. Anil Nerode, Cornell University). Member of the scientific advisory board of the European Association for Computer Science Logic (EACSL), of the European Association of Theoretical Computer Science (EATCS), of the Kurt Gödel society (KGS; vice president of this society from 1990-1995), of the institute of computer science of the Consiglio Nazionale delle Ricerche (CNR) in Cosenza, Italy, and of the SOFSEM Seminars in the Czech Republic. Chair of the ACM PODS Executive committee (2004-2006) and General Chair of the PODS conferences of 2005 and 2006.
Membership of EU Networks of Excellence:
Network of Excellence COLOGNET (Computational Logic), GAMES (Games-Theory and Logic), REWERSE Foundations of the Semantic Web).In the past: COMPULOG (Computational Logic) and IDOMENEUS (databases).