Vorträge des SFB 1442

Abstract: We briefly review the tautological ring of the moduli space of surfaces, before discussing how to define the analogous ring for the moduli space of 3-dimensional handlebodies (and more generally, odd-dimensional manifolds with boundary). We then discuss some sheaf-theoretic methods of probing the structure of this ring. The talk is based on ongoing work that will (hopefully) appear in my PhD thesis this summer.

Abstract: The ?-category Cond(Ani) of condensed anima combines the homotopy-theoretic direction of anima with the topological space direction of condensed sets. For example, we can recover the shape of a sufficiently nice topological space from the corresponding condensed anima. My talk will focus on a joint refinement of the etale homotopy type and the pro-etale fundamental group of a scheme, realised as an object in Cond(Ani). This is closely related to work of Barwick, Glasman and Haine on exodromy. I will give an overview of results from my dissertation and an ongoing project jointly with Haine, Holzschuh, Lara and Wolf.

Guentner, Willet and Yu defined a notion of dynamic asymptotic dimension for an etale groupoid that can be used to bound the nuclear dimension of its groupoid C*-algebra. To have finite dynamic asymptotic dimension, the isotropy subgroups of the groupoid must be locally finite. I will discuss 1) how to use similar ideas to bound the nuclear dimension of the C*-algebra of a groupoid with `large' isotropy subgroups and 2) the limitations of that approach. In an application to the C*-algebra of a directed graph, if the C*-algebra is stably finite, then its nuclear dimension is at most 1. This is joint work with Dana Williams.

Abstract: The study of descent properties of K-theory plays an important role in understanding its values and behaviour in many geometric contexts. In this talk, I will explain a construction of certain diagrams arising from formal gluing situations for which continuous K-theory, and more generally all localising invariants, satisfy descent, from the perspective of dualisable categories. I will also discuss how this encompasses both Clausen?Scholze?s gluing result for analytic adic spaces and an adelic descent result for dualisable categories.

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