MULTIPLY ACCELERATED VALUE ITERATION FOR NONSYMMETRIC AFFINE FIXED POINT PROBLEMS AND APPLICATION TO MARKOV DECISION PROCESSES

We analyze a modified version of the Nesterov accelerated gradient algorithm, which applies to affine fixed point problems with non-self-adjoint matrices, such as the ones appearing in the theory of Markov decision processes with discounted or mean payoff criteria. We characterize the spectra of matrices for which this algorithm does converge with an accelerated asymptotic rate. We also introduce a dth-order algorithm and show that it yields a multiply accelerated rate under more demanding conditions on the spectrum. We subsequently apply these methods to develop accelerated schemes for nonlinear fixed point problems arising from Markov decision processes. This is illustrated by numerical experiments.