Using Generalized Learning Automata for State Space Aggregation in MAS

A key problem in multi-agent reinforcement learning remains dealing with the large state spaces typically associated with realistic distributed agent systems. As the state space grows, agent policies become more and more complex and learning slows. One possible solution for an agent to continue learning in these large-scale systems is to learn a policy which generalizes over states, rather than trying to map each individual state to an action. In this paper we present a multi-agent learning approach capable of aggregating states, using simple reinforcement learners called learning automata (LA). Independent Learning automata have already been shown to perform well in multi-agent environments. Previously we proposed LA based multi-agent algorithms capable of finding a Nash Equilibrium between agent policies. In these algorithms, however, one LA per agent is associated with each system state, as such the approach is limited to discrete state spaces. Furthermore, when the number of states increases, the number of automata also increases and the learning speed of the system slows down. To deal with this problem, we propose to use Generalized Learning Automata (GLA), which are capable of identifying regions within the state space with the same optimal action, and as such aggregating states. We analyze the behaviour of GLA in a multi-agent setting and demonstrate results on a set of sample problems.