Abstract

This paper introduces a new class of non-convex vector functions strictly larger than that of P-quasiconvexity, with P ? ?m being the underlying ordering cone, called semistrictly ( [InlineMediaObject not available: see fulltext.] m \ -int P)-quasiconvex functions. This notion allows us to unify various results on existence of weakly efficient (weakly Pareto) optima. By imposing a coercivity condition we establish also the compactness of the set of weakly Pareto solutions. In addition, we provide various characterizations for the non-emptiness, convexity and compactness of the solution set for a subclass of quasiconvex vector optimization problems on the real-line. Finally, it is also introduced the notion of explicit ( [InlineMediaObject not available: see fulltext.] m \ -int P)-quasiconvexity (equivalently explicit (int P)-quasiconvexity) which plays the role of explicit quasiconvexity (quasiconvexity and semistrict quasiconvexity) of real-valued functions. © Springer-Verlag 2004.