SEMI-PRECONVEX SETS ON PRECONVEXITY SPACES Min, Won-Keun;
In this paper, we introduce the concept of the semi-preconvex set on preconvexity spaces. We study some properties for the semi-preconvex set. Also we introduce the concepts of the sc-convex function and -convex function. Finally, we characterize sc-convex functions, -convex functions and semi-preconvex sets by using the co-convexity hull and the convexity hull.