April 27th 2017; 12:00 auditorium of the CRM
Joachim Cuntz. Semigroup C*-algebras and toric varieties

Abstract: The coordinate ring of a toric variety is the semigroup ring of a finitely generated subsemigroup of Z n . Such semigroups have the interesting feature that their family of constructible ideals is not independent. This is reflected by torsion phenomena in the K -theory of the semigroup C ∗ -algebra. We give a complete formula for the K -theory in the case of subsemigroups of Z 2 .