Skew-product graphs and C*-coactions


March 21 and 28, and April 4, 2024: S. Kaliszewski, ASU Skew-product graphs and C*-coactions

Abstract: Given a directed graph E, a discrete group G, and a labeling c of the edges of E by elements of G, one can construct a skew-product graph ExG. It turns out that c also gives rise to a coaction of G on the graph algebra C*(E), and that the resulting crossed product C*(E)xG is isomorphic to C*(ExG): So graph labelings are somehow ``coactions we can see''. In these talks, I'll use skew-product graphs to motivate the basic ideas behind coactions of groups on C*-algebras, and to illustrate how crossed-product duality works in this context. Time permitting, I'll also indicate how the skew-product construction can be extended to other graph-like contexts with similar results.



C*-Algebra Seminar
Thursday, April 4
3:00-4:00pm MST (UTC-7)
ASU Tempe - WXLR 546

Organizers: S. Kaliszewski and Jack Spielberg


Steve Kaliszewski,
Arizona State University

WXLR 546