A Formal Model for Situated Multi-Agent Systems

Issue title: Multiagent Systems (FAMAS'03)

Article type: Research Article

Authors: Weyns, Danny | Holvoet, Tom

Affiliations: AgentWise, DistriNet, Department of Computer Science, K.U. Leuven, Belgium

Abstract: Contrary to cognitive approaches of agency where a lot of effort is devoted to the formalization of agent concepts, little work has been done on the formalization of situated multi-agent systems (situated MASs). In this paper we present a generic model for situated MASs. This model formally describes an abstract architecture for situated MASs. In this architecture each agent is situated in its local context that it is able to perceive and in which it can act. Since intelligence in situated MASs results from the interactions of agents with the environment rather than from their individual capabilities, the model takes an action-centric approach. The model deals with (1) the actions of agents in the environment, (2) ongoing activities in the environment, such as moving objects, and (3) the interactions between agents and ongoing activities through the environment. One model for situated MASs was described by J.Ferber and J.P. M¨ller. In this model all agents of the MAS act at one global pace, i.e.the agents are globally synchronized. Drawbacks of global synchronization are centralized control and poor scalability. We present a model that allows agents to synchronize locally. In this model there is no centralized entity that imposes all agents to act at one global pace, but instead agents themselves decide when they perform their next actions. The model supports simultaneous actions through regional synchronization. With regional synchronization agents form synchronized groups on the basis of their actual locality. Different groups can act asynchronously, while agents within one group act synchronously. The result is a model that does not suffer from the drawbacks of global synchronization while it preserves the properties for handling simultaneous actions. In the paper we apply the model to a simple MAS application. We show how the abstract model can be instantiated for a practical application. Then we follow a trace in the evolution of the application and demonstrate how the model deals with each particular step.

Journal: Fundamenta Informaticae, vol. 63, no. 2-3, pp. 125-158, 2004