Optimal Problem Distribution by 2-Way Circulation Board Protocol

Abstract

How to distribute a problem to the appropriate agent (solver) is one technical problem in distributed problem solving. As the agent's solving ability is changeable according to the environment, the dynamic distribution method by 'message passing' is more suitable than the static one by 'global directory'. Contract Net (CN) Protocol, by announce-bit-award message passing, is well known as the dynamic distribution method, but its shortcomming is the difficulty of optimal distribution. When several agents have their own problems, it is difficult to distribute them to the appropriate agents in a global view. The difficulty is caused by the locality of information needed for problem distribution, and by message delay. To cope with such difficulty, we devised 2-way Circulation Board (CB) Protocol. In CB Protocol, agents are linked as a ring, and each agent can circulate a message around agents. By the property of 2-way message circulation, each agent can get the global information to distribute problems, and by the property of message never passing the other message, it is easy to synchronize the agent's action. In this paper, we suggest the optimal problem distribution method by 2-way CB Protocol.