EXISTENCE AND NON-EXISTENCE RESULTS OF SOLUTIONS OF CERTAIN CLASSES OF PARTIAL DIFFERENTIAL EQUATIONS AND SYSTEMS

Abstract

This thesis contain a results of the existence of positive solutions of certain nonlinear elliptic and parabolic systems, involving the (p; q)-Laplace and the p(x)-Laplace operators. The method used to obtain the results is that of sub and supersolution, which is based on the maximum principle and the comparison theorem.