On Communication in Solving Distributed Constraint Satisfaction Problems

Abstract

Distributed Constraint Satisfaction Problems (DCSP) is a general framework for multi-agent coordination and conflict resolution. In most DCSP algorithms, inter-agent communication is restricted to only exchanging values of variables, since any additional information-exchange is assumed to lead to significant communication overheads and to a breach of privacy. This paper provides a detailed experimental investigation of the impact of inter-agent exchange of additional legal values among agents, within a collaborative setting. We provide a new run-time model that takes into account the overhead of the additional communication in various computing and networking environments. Our investigation of more than 300 problem settings with the new run-time model (i) shows that DCSP strategies with additional information-exchange can lead to big speedups in a significant range of settings; and (ii) provides categorization of problem settings with big speedups by the DCSP strategies based on extra communication, enabling us to selectively apply the strategies to a given domain. This paper not only provides a useful method for performance measurement to the DCSP community, but also shows the utility of additional communication in DCSP.