“…By using Ekeland's theorem, they gave a characterization of Tykhonov's well-posedness for a minimizing problem with a convex lower semi-continuous function on a closed convex set. Since then, various kinds of well-posedness for optimization problems, such as LP well-posedness and generalized well-posedness etc., are extended to develop the well-posedness for variational inequalities and their related problems, such as equilibrium problems, fixed point problems, inclusion problems and others; see e.g., [3,11,14,17,20].…”