Developing Alternative Mechanisms for Multiagent Coordination

Abstract

Coordination is a key functionality and maybe the most challenging research issue in multiagent systems, and mechanisms for achieving coordinated behavior have been well-studied. One important observation has been that different mechanisms have correspondingly different performance characteristics, and that these can change dramatically in different environments (i.e., no one mechanism is best for all domains). A more recent observation is that one can describe possible mechanisms in a domain-independent way, as simple or complex responses to certain dependency relationships between the activities of different agents. Thus agent programmers can separate encoding agent domain actions from the solution to particular coordination problems that may arise. This paper explores the specification of a large range of coordination mechanisms for the common hard enablement (or happens-before) relationship between tasks at different agents. Essentially, a coordination mechanism can be described as a set of protocols possibly unique to the mechanism, and as an associated automatic re-writing of the specification of the domain-dependent task (expressed as an augmented HTN). This paper also presents a concrete implementation of this idea in the DECAF. A novel GPGP coordination component, between the planner and the scheduler, is developed in the DECAF agent architecture. An initial exploration of the separation of domain action from meta-level coordination actions for four simple coordination mechanisms is explained then.