Automatica, Vol.42, No.4, 637-644, 2006
Actor-critic algorithms for hierarchical Markov decision processes
We consider the problem of control of hierarchical Markov decision processes and develop a simulation based two-timescale actor-critic algorithm in a general framework. We also develop certain approximation algorithms that require less computation and satisfy a performance bound. One of the approximation algorithms is a three-timescale actor-critic algorithm while the other is a two-timescale algorithm, however, which operates in two separate stages. All our algorithms recursively update randomized policies using the simultaneous perturbation stochastic approximation (SPSA) methodology. We briefly present the convergence analysis of our algorithms. We then present numerical experiments on a problem of production planning in semiconductor fabs on which we compare the performance of all algorithms to-ether with policy iteration. Algorithms based on certain Hadamard matrix based deterministic perturbations are found to show the best results. (c) 2006 Elsevier Ltd. All rights reserved.
Keywords:hierarchical decision making;learning algorithms;Markov decision processes;stochastic approximation;optimal control