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Semigroup $C^{\ast }$-algebras and toric varieties

Joachim Cuntz

3:00 pm - 4:00 pm, March 31th, 2017   Science Building A1510

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 $C^{\ast }$-algebra. We give a complete formula for the K-theory in the case of subsemigroups of Z${}^2$.

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