Operator Theory Seminar

Speaker: 
Ruy Exel, University of Nebraska @ Lincoln
Topic: 
"Weak Cartan inclusions and non-Hausdorff groupoids"

Abstract:
Given a not-necessarily Hausdorff, topologically free, twisted ´etale groupoid $(\mathcal{G},\mathcal{L})$, we consider its essential groupoid $C^*$-algebra, denoted $C^{*}_{ess}(\mathcal{G},\mathcal{L})$, obtained by completing $\mathcal{C}_{c}(\mathcal{G},\mathcal{L})$ with the smallest among all $C^*$-seminorms coinciding with the uniform norm on $C_{c}(\mathcal{G}^{(0)})$. The inclusion of $C^*$-algebras "$C_{0}(\mathcal{G}^{(0)})\subseteq C^{*}_{ess}(\mathcal{G},\mathcal{L})$" is then proven to satisfy a list of properties characterizing it as what we call a weak Cartan inclusion. We then prove that every weak Cartan inclusion "$A\subseteq B$", with $B$ separable, is modeled by a twisted ´etale groupoid, as above. This talk is based on joint work with D. Pitts.

Event Date: 
February 15, 2019 - 10:30am to 11:30am
Location: 
213 MLH
Calendar Category: 
Seminar
Seminar Category: 
Operator Theory