After two successful MATES conferences in Erfurt 2003 and 2004, the 3rd G- man conference on Multi-agent System Technologies (MATES 2005) took place in Koblenz, Germany, in September 2005, and was co-located with the 28th German Conference on Arti?cial Intelligence (KI 2005).

Invited Contributions.- On the Convergence of Structured Search, Information Retrieval and Trust Management in Distributed Systems.- Semantic Methods for P2P Query Routing.- Programming Cognitive Agents.- Workflows and Group Interaction.- Enacting the Distributed Business Workflows Using BPEL4WS on the Multi-agent Platform.- BSCA-P: Privacy Preserving Coalition Formation.- Towards Service Coalitions: Coordinating the Commitments in a Workflow.- Reasoning about Utility.- Modeling Minority Games with BDI Agents – A Case Study.- A Goal Deliberation Strategy for BDI Agent Systems.- Estimating Utility-Functions for Negotiating Agents: Using Conjoint Analysis as an Alternative Approach to Expected Utility Measurement.- The Dynamics of Knowledge.- Reconciling Agent Ontologies for Web Service Applications.- An Agent-Based Knowledge Acquisition Platform.- An Agent Architecture for Ensuring Quality of Service by Dynamic Capability Certification.- Engineering a Multi Agent Platform with Dynamic Semantic Service Discovery and Invocation Capability.- Methodology and Simulation.- Towards a Formal Methodology for Designing Multi-agent Applications.- LEADSTO: A Language and Environment for Analysis of Dynamics by SimulaTiOn.- Agent Tools and Agent Education.- Towards a Distributed Tool Platform Based on Mobile Agents.- The Distributed Weighing Problem: A Lesson in Cooperation Without Communication.- Short Papers.- An Adaptive Reputation Model for VOs.- Realising Reusable Agent Behaviours with ALPHA.- Multi-agent System Specification Using TCOZ.- ABACO, Coordination of Autonomous Entities.- Agent-Based Simulation for Testing Control Software of High Bay Warehouses.- Posters.- Collaborative Agent-Based Knowledge Support for Empirical and Knowledge-Intense Processes.- Experiments inNeo-computation Based on Emergent Programming.- A Framework Based on Multi-agent Systems for Information Retrieval Through Mobile Devices.- CASCOM: Context-Aware Service Co-ordination in Mobile P2P Environments.