A cooperative search scheme for dynamic problems

The importance of building a general framework for distributed problem solving is coming to be acknowledged. Distributed search is one of such frameworks and defined as finding a required path in a given graph by cooperation of multiple agents, each of which is able to search the graph partially. In this paper, the authors propose a new cooperative search scheme for dynamic problems where costs of links are changeable in the course of the search. To cope with the dynamic character, agents cooperate with each other by exchanging cost information that they keep. When a large amount of cost information is exchanged, it improves the quality of solution, but on the other hand it raises communication overhead. It is hence significant to know how much cost information optimizes the total performance. The authors developed a testbed that simulates a communication network and applied their scheme to a routing problem which can be viewed as a dynamic problem where cost of link is defined as changeable communication delay. The authors measured its performance according to the amount of the cost information exchanged among agents