Optimal control of unilateral obstacle problem with a source term (Q1029224)

It is considered an optimal control problem for a linear second-order elliptic inequality. The control function is the obstacle function. The main difficulty of this type problem comes from the fact that the mapping between the control and the state is not differentiable. The authors give an approximation of the control problem and obtain an optimality conditions system for approximating problem and original problem, by passing to the limit with respect to a parameter of approximation.