A SIMPLE PROOF OF THE APPROXIMATE CONTROLLABILITY FROM THE INTERIOR FOR NONLINEAR EVOLUTION PROBLEMS

The approximate controllability property for solutions of a large clas s of nonlinear evolution problems is obtained under some abstract cond itions which hold, for instance, when the control is the right hand si de of the equation. Our very simple method put in evidence the indepen dence between the solvability of a boundary value problems and the stu dy of the approximate controllability property which takes places in a number of cases. No duality type arguments are used which allows the consideration of very general nonlinear problems.