Expediting RL by using graphical structures

The goal of Reinforcement learning (RL) is to maximize reward (minimize cost) in a Markov decision process (MDP) without knowing the underlying model a priori. RL algorithms tend to be much slower than planning algorithms, which require the model as input. Recent results demonstrate that MDP planning can be expedited, by exploiting the graphical structure of the MDP. We present extensions to two popular RL algorithms, Q-learning and RMax, that learn and exploit the graphical structure of problems to improve overall learning speed. Use of the graphical structure of the under- lying MDP can greatly improve the speed of planning algorithms, if the underlying MDP has a nontrivial topological structure. Our experiments show that use of the apparent topological structure of an MDP speeds up reinforcement learning, even if the MDP is simply connected.