Equidimensionality of convolution morphisms and applications to saturation problems

Abstract

We study the fibers of Mirkovic-Vilonen convolution morphisms. We prove their equidimensionality when all the coweights in question are minuscule, and some related statements. We give applications to saturation problems for structure constants of Hecke and representation rings. An erratum has been added to correct insufficiencies in the proofs of Lemma 9.4 and Corollary 9.5 as they appeared in the published version.