Constraints, 7, 5–6, 2002© 2002 Kluwer Academic Publishers. Manufactured in The Netherlands.

Special Issue on Constraint Agents

PEGGY S. EATONUniversity of New Hampshire, Durham, NH 03824

THOM FRUEHWIRTHLudwig-Maximilians-Universitaet-Muenchen (LMU), D-80538 Munich, Germany

MILIND TAMBEUniversity of Southern California, Los Angeles, CA 03802-3070

The articles in this special issue explore constraint techniques for effectively handlingagent control, team cooperation and coordination, as well as for improving performancein applications such as electronic commerce and information gathering systems.In these articles, constraint-based techniques are applied to agent research challenges:

• agent control in real-time, multi-agent, dynamic environments

• multi-agent collaboration, cooperation, communication, and competition amongfriendly and hostile agents

• multi-agent negotiation over limited resources with partial knowledge

• strategies for reasoning about individual agent roles and team organizations

• multi-agent systems as models for studying complex systems

• user interface agents or user interfaces for agent systems

The constraint paradigm is extended:

• to support agents in a dynamic, real-time environment

• to classify constraints used in a multi-agent system

• to support user interaction during problem solving

• to provide methodologies for building scalable agent systems

• to provide a mechanism for incremental computation while maintaining partialsolutions

The article by Yu Zhang and Alan K. Mackworth describes control in a multi-agent,real-time, dynamic system where agents interact to solve problems beyond the knowledgeand capabilities of the individual agents. The Constraint Nets formalism is used to modeland control the dynamic real-time system. Agent strategies for operating with friendly

6 P. S. EATON, T. FRUEHWIRTH AND M. TAMBE

team members and adversarial opponents are explored in the context of agent roles andteam organization.The paper by Yan Qu and Steve Beale examines how agents detect and resolve sit-

uations in which the user’s information needs have been over-constrained. The authorsextend constraint satisfaction, solution synthesis, and constraint hierarchy techniques toprovide an incremental computational mechanism for constructing and maintaining par-tial parallel solutions. Knowledge in the solution synthesis network is used to developrelaxation strategies to support cooperative dialogues.The article by Marc Torrens, Boi Faltings, and Pearl Pu explores the use of constraint

satisfaction methods to actively support the user during the problem solving process. Theauthors present methods to reduce complexity while providing scalable applications ininformation agents of the future.Software agents and multi-agent systems provide a wide-range of opportunities for

theoretical and practical applications of constraints. Constraint-based reasoning can beuseful in agent-based systems to allow agents to reason about available computationalresource constraints or reach compromises in negotiations over limited resources. Theresearch in these articles suggests that future intelligent agent systems will continueto address these problems and will emphasize integrated and hierarchical processing inwhich agents interact in a coordinated and timely manner.