INVERSE REINFORCEMENT LEARNING METHOD, STORAGE MEDIUM FOR STORING INSTRUCTION TO EXECUTE PROCESSOR FOR PROCESS FOR INVERSE REINFORCEMENT LEARNING, SYSTEM FOR INVERSE REINFORCEMENT LEARNING, AND PREDICTION SYSTEM INCLUDING SYSTEM FOR INVERSE REINFORCEMENT LEARNING

摘要

A method of inverse reinforcement learning for estimating cost and value functions of behaviors of a subject includes acquiring data representing changes in state variables that define the behaviors of the subject; applying a modified Bellman equation given by Eq. (1) to the acquired data: q(x)+gV(y)−V(x)=−1n{pi(y|x))/(p(y|x)} (1) where q(x) and V(x) denote a cost function and a value function, respectively, at state x, g represents a discount factor, and p(y|x) and pi(y|x) denote state transition probabilities before and after learning, respectively; estimating a density ratio pi(y|x)/p(y|x) in Eq. (1); estimating q(x) and V(x) in Eq. (1) using the least square method in accordance with the estimated density ratio pi(y|x)/p(y|x), and outputting the estimated q(x) and V(x).