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Affine images of compact convex sets and maximal measures

Publication at Faculty of Mathematics and Physics |
2009

Abstract

Let $\phi:X\to Y$ be an affine continuous mapping of a compact convex set X onto a compact convex set Y. We show that the induced mapping $\phi#$ need not map maximal measures on X to maximal measures on Y even in case $\phi$ maps extreme points of X to extreme points of Y.

This disproves Théoréme 6 of [S. Teleman, Sur les mesures maximales, C.

R. Acad.

Sci. Paris Sér.

I Math. 318 (6) (1994) 525-528]. We prove the statement of Théoréme 6 under an additional assumption that extY is Lindelöf or Y is a simplex.

We also show that under either of these two conditions injectivity of $\phi$ on extX implies injectivity of $\phi#$ on maximal measures. A couple of examples illustrate the results.