Published online by Cambridge University Press: 26 February 2010
It is well known that every set of at least d + 2 points of ℝd may be decomposed into two disjoint parts whose convex hulls intersect. This result, called Radon's theorem, has been generalized in different ways. The easiest generalization consists in replacing the field of real numbers by any ordered division ring (field or skew-field): here the original proof remains valid. A less immediate generalization is the following one, conjectured by Birch [1] and proved by Tverberg [3]:
Every set of at least r(d + 1) – d points of ℝd may be decomposed into r disjoint parts whose convex hulls intersect.