Quasiconvex Sets

Abstract
Introduction. Let I be the closed real number interval: Any subset Δ of I containing at least one number interior to I, will be called a quasiconvexity generating set. To each quasiconvexity generating set Δ we associate as follows a generalized notion of convexity, here called quasiconvexity or Δ convexity. Two numbers α and β, one of which belongs to Δ, the other being determined by the relation a α + β = 1, are called complementary ratios of Δ. A set Q in a real vector space is said to be A convex if for every pair of complementary ratios α and β in Δ and every pair of points a and b lying in Q the point αa +β b also lies in Q.