The stochastic maximum principle in optimal control of singular diffusions with non linear coefficients

Abstract

We consider a stochastic control problem of a non linear system in which the variable control has two components, the first being absolutely continuous and the second singular. We assume a convex state constraint, a non convex cost criterion and we allow the absolutely continuous component of the control to enter both the drift and diffusion coefficients. The maximum principle is established by using mainly a convex perturbation on a given optimal control. This result generalizes at the same time the result obtained by Cadellinas-Haussman as well as that obtained by Bensoussan.