Characterizations of efficient solutions under polyhedrality assumptions

The paper gives several characterizations of efficient solutions of subsets of R^p (with respect to compatible preorders) in terms of the lexicographical order, under the assumptions that the set of admissible points is a convex polyhedron or the nonnegative cone corresponding to the preorder is polyhedral. It also characterizes the lexicographical minimum of a convex polyhedron by means of the componentwise order and unitary lower triangular matrices.