1 Distributed Belief Revision Benedita Malheiro, Eugénio Oliveira and Nick Jennings Benedita Malheiro Dept. of Electrical Engineering, Instituto Superior de Engenharia do Porto, Rua de S. Tomé, 4200 Porto, Portugal. Telephone: +351-2-82 11 34 Fax: +351-2-82 11 29 Email: mbnm@fe.up.pt Eugénio Oliveira Dept. of Electrical Engineering and Computers, Faculty of Engineering, Opporto University, Rua dos Bragas - 4099 Porto CODEX, Portugal. Telephone: +351-2-200-7505 Fax: +351-2-319-280 Email: eco@fe.up.pt Nick Jennings Department of Electronic Engineering, Queen Mary & Westfield College, University of London, Mile End Road, London E1 4NS, UK. Telephone: +44-71-975-5349 Fax: +44-81-981-0259 Email: N.R.Jennings@qmw.ac.uk Content Areas: Distributed Reasoning and Control; Cooperation; Belief Revision. Abstract The ability to respond sensibly to changing and conflicting beliefs is an integral part of intelligent agency. To this end, we outline the design and implementation of a Distributed Assumption-based Truth Maintenance System (DATMS) appropriate for controlling cooperative problem solving in a dynamic real world multi-agent community. Our DATMS works on the principle of local coherence which means that different agents can have different perspectives on the same fact provided that these stances are appropriately justified. The belief revision algorithm is presented, the meta-level control actions needed to ensure that all system-wide queries can be uniquely answered is described, and the DATMS' implementation in a general purpose multi-agent shell is discussed.