Some remarks ons-convex functions

SummaryTwo kinds ofs-convexity (0 <s ≤ 1) are discussed. It is proved among others thats-convexity in the second sense is essentially stronger than thes-convexity in the first, original, sense whenever 0 <s < 1. Some properties ofs-convex functions in both senses are considered and various examples and counterexamples are given.