“…The existence results have been applied to optimal control problems governed by partial differential equations, see, for example, [3,4,6,[8][9][10]14,24]. Here we are especially interested in the study of the problem (x, J )-sup; while, for the problem (x, J )-inf, the readers are referred to [6,10,11,20,26]. In [5], it was proved that if X is a reflexive and locally uniformly convex Banach space then the set of all x ∈ X for which the problem (x, J )-sup has a solution is a dense G δ -subset of X.…”