MAXIMUM PRINCIPLE AND EXISTENCE OF SOLUTIONS FOR NON-NECESSARILY COOPERATIVE SYSTEMS INVOLVING SCHROÖ DINGER OPERATORS.

In this paper, we obtain the necessary and sufficient conditions for having the maximum principle and existence of positive solutions for some cooperative systems involving Schrödinger operators defined on unbounded domains. Then, we deduce the existence of solutions for semi-linear systems. Finally we discuss the generalized maximum principle (ϕq- positivity) for non-cooperative systems. [ABSTRACT FROM AUTHOR]