Right quadruple convexity
Dandan Li, Liping Yuan, Tudor I. Zamfirescu · Ars Mathematica Contemporanea · 2017
A set of four points w, x, y, z ∈ Rd (always d ≥ 2) form a rectangular quadruple if their convex hull is a non-degenerate rectangle. The set M is called rq-convex if for every pair of its points we can find another pair in M, such that the four points form a rectangular quadruple. In this paper we start the investigation of rq-convexity in Euclidean spaces.