Murphy's Law for gerbes

Online seminar on Quadratic Forms, Linear Algebraic Groups and Beyond, 8:30-9:30am

https://uottawa-ca.zoom.us/j/99397061432?pwd=LzNBS1UrSVNJQ1ZiU28yWHAyNlV...

This is a report on joint work with Daniel Bragg. We study what gerbes are possible as residual gerbes in natural moduli stacks. Among other things, we show that every gerbe with finite structure group arises as a residual gerbe in the stack of smooth projective curves. This gives examples of "versal gerbes" that arise organically in algebraic geometry. The key to producing such things is the transport of various classical constructions from equivariant geometry to corresponding constructions for spaces over non-trivial gerbes.