Learning equilibria in games by stochastic distributed algorithms

Abstract

We consider a family of stochastic distributed dynamics to learn equilibria in games, that we prove to correspond to an Ordinary Differential Equation (ODE). We focus then on a class of stochastic dynamics where this ODE turns out to be related to multipopulation replicator dynamics.Using facts known about convergence of this ODE, we discuss the convergence of the initial stochastic dynamics. For general games, there might be non-convergence, but when the convergence of the ODE holds, considered stochastic algorithms converge towards Nash equilibria. For games admitting a multiaffine Lyapunov function, we prove that this Lyapunov function is a super-martingale over the stochastic dynamics and that the stochastic dynamics converge. This leads a way to provide bounds on their time of convergence by martingale arguments. This applies in particular for many classes of games considered in literature, including several load balancing games and congestion games. © 2013 Springer-Verlag London.