Abstract: This is the Euclidean Wick rotated analogue of Feynman's formula for the propagator. Unlike the latter, it can be rigorously proved. I shall first define the Wiener measure on the space of continuous paths and then prove the formula. I end with a few examples and applications.

Abstract: This talk is based on ongoing work with X. Tang and H. Tseng that grew out of my attempt to understand a certain duality for gerbes on orbifolds that Tang and Tseng studied in their paper "Duality theorems of etale gerbes on orbifolds". Our new approach is more conceptual, allowing the definition of duality to be extended in greater generality. In the talk I will explain gerbes from the point of view of bitorsors and sketch the constructions involved in duality, both original and twisted.

Abstract: