sublinear functional, Derivatives of functions in infinite-dimensional spaces, Rockafellar's maximal monotonicity theorem, Nonsmooth analysis, Ekeland's variational principle, Theorems of Hahn-Banach type; extension and lifting of functionals and operators, existence of subtangents, maximal monotone operator, Geometry and structure of normed linear spaces, convex lower surface, Hahn-Banach theorem, directional derivative of a convex function, Applications of operator theory in optimization, convex analysis, mathematical programming, economics, epigraphs of proper convex lower semi-continuous functions, maximal monotonicity, subdifferentials, Set-valued operators, bounded closed convex sets