C*-Extreme Points and C*-Faces oF the Epigraph iF C*-Affine Maps in *-Rings

Abstract

Abstract. In this paper, we define the notion of C*-affine maps in the<br /> unital *-rings and we investigate the C*-extreme points of the graph<br /> and epigraph of such maps. We show that for a C*-convex map f on a<br /> unital *-ring R satisfying the positive square root axiom with an additional<br /> condition, the graph of f is a C*-face of the epigraph of f. Moreover,<br /> we prove some results about the C*-faces of C*-convex sets in *-rings.<br /> Keywords: C*-affine map, C*-convexity, C*-extreme point, C*-face.<br /> MSC(2010): Primary: 52A01; Secondary: 16W10, 46L89.