This book constitutes the refereed proceedings of the 4th International Conference on Coordination Languages and Models, COORDINATION 2000, held in Limassol, Cyprus in September 2000.The 18 revised full papers and nine short papers presented were carefully reviewed and selected from 52 submissions. The papers are organized in topical sections on coordination styles and trends, tuple space semantics and implementation, coordination policies, dynamics of coordination, mobility, semantic models, shifting Linda perspectives, directions in software architecture, achieving software dependability.

The Portuguese Association for Artificial Intelligence has been organizing Portuguese Conferences on Artificial Intelligence, now held every second year, since 1985. This volume contains selected papers from the Fifth Conference on Artificial Intelligence. The conference has an international status: 62 contributions from 13 countries were received, of which 26 were from Portugal. To guarantee a high scientific standard, all the contributions were reviewed by at least three researchers, and only 20 papers were accepted and included in these proceedings. The papers are organized into sections on constraints, search, knowledge representation, temporal reasoning, planning, diagnosis and repair, and learning.