Abstract
Typical methods for solving reinforcement learning problems iterate two steps, policy evaluation and policy improvement. This study proposes algorithms for the policy evaluation to improve learning efficiency. The proposed algorithms, based on the Krylov Subspace Method (KSM), are tens to hundreds times more efficient than existing algorithms based on the Stationary Iterative Methods (SIM). Algorithms based on KSM are far more efficient than they have been generally expected. This study clarifies what makes algorithms based on KSM makes more efficient with numerical examples and theoretical discussions.