Mixed formulation of elliptic variational inequalities and its approximation

The approximation of a mixed formulation of elliptic variational inequalities is studied. Mixed formulation is defined as the problem of finding a saddle-point of a properly chosen Lagrangian $\Cal 2$ on a certain convex set $Kx \ \Lambda$. Sufficient conditions, guaranteeing the convergence of approximate solutions are studied. Abstract results are applied to concrete examples.