“…The theory of variational inequalities was initially developed to deal with equilibrium problems, precisely the Signorini problem. After that it has been extended and generalized to study a wide class of problems arising in mechanics, physics, optimization and control, nonlinear programming, economics, finance, regional structural,transformation, elasticity, and applied sciences, etc., see e.g., [1,2,4,12,15,16,17,18,19,20] and references therein.…”