Topology Atlas Document # paao-46


On Aumann's Theorem that the sphere does not admit a mean

F. Javier Trigos-Arrieta and Marian Turzanski

Topology Atlas Preprint # 542

We prove that the circle S1 does not have a 2-mean, i.e., S1×S1 cannot have a retraction r onto its diagonal with r(x, y)=r(y, x), whenever x, y in S1. Our proof is combinatorial and topological rather than analytical.

Date received: November 20, 2003.


Copyright © 2003 by the authors. Distributed by Topology Atlas with permission of the authors.