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Elke Enning

Elizabeth Gillaspy (Missoula): K-theory for real k-graph C*-algebras. Oberseminar C*-Algebren.

Tuesday, 31.05.2022 16:15 im Raum SRZ 216/217

Mathematik und Informatik

Purely infinite simple real C*-algebras, like their complex counterparts, are classified by their K-theory. Indeed, there are purely infinite simple real C*-algebras (e.g. the exotic Cuntz algebra E_n) whose existence was first identified thanks to K-theory computations. Our long-term goal, in this joint research project with Jeff Boersema, is to construct more concrete models for such C*-algebras. We begin by showing how k-graphs, or higher-rank graphs (which are a higher-dimensional generalization of directed graphs), can give rise to purely infinite simple real C*-algebras. To evaluate whether this class of real k-graph C*-algebras includes E_n, we need to compute the K-theory of real k-graph C*-algebras. To that end, we adapt the spectral sequence studied by D.G. Evans, which converges to the K-theory of a complex k-graph C*-algebra, to the setting of real C*-algebras. Using this spectral sequence, we compute K-theory for several examples of real k-graph C*-algebras. In particular, we exhibit an example of a 7-graph whose C*-algebra is the stabilized exotic Cuntz algebra. This is joint work with Jeff Boersema (and in part, ongoing joint work also with Sarah Browne).



Angelegt am 14.04.2022 von Elke Enning
Geändert am 25.05.2022 von Elke Enning
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