Katsutoshi Hirayama and Jun'ichi Toyoda
When multiple agents solve their own problems while they interact with each other, it is helpful to form a coalition, which is a group of agents working together. Previous approaches to coalition formation have proposed to define the utility of coalitions and to use a strategy that agents form coalitions for getting higher utility. However, in some problems, the utility of coalitions is not easily obtainable because it might depend on various uncertain things. This paper describes a model of coalition formation where agents form coalitions for breaking deadlocks. In this model, agents solve Distributed Constraint Satisfaction Problems with an iterative repair method, and form coalitions when they get stuck at local minima. This model is suggested to realize a new approach to coalition formation. We also present problem solving strategies in coalitions: the selfish and the altruistic. These two strategies differ in the way to build a domain of variables. From our experimental results on distributed 3-coloring problems, the altruistic group performed better than the selfish group.