A. AVERNA and T. CARDINALI
Sui concetti di K-convessitā (K-concavitā)e di K-convessitā* (K-concavitā*)
Received: 18 July 1990
Abstract In this note we prove for a set. valued function <<F>> various theorems giving relations between the <<K-continuity>> condition and the notions of <<K-convexity>> , <<K-concavity>> , <<K-convexity*>> and <<K-concavity*>> . The principal results here obtained contain the classical Bernstein-Doetsch theorenm and contain or extend theorems due to K. Nikodem.