Equivariant bordism of surfaces and counterexamples to the evenness conjecture

-
Eric Samperton,听University of Illinois at Urbana-Champaign

Online Talk听

Zoom link:听

Passcode: 998749

Let G be a finite group. 听The G-equivariant bordism ring is a module over the usual (non-equivariant) bordism ring. It was observed in various works in the 1970s that for G abelian or metacyclic, the G-equivariant unitary bordism ring is a free module with generators in even degrees. Later Comeza帽a conjectured this should be true for general G, and then Uribe promoted the problem at ICM 2018, where he called it the 鈥渆venness conjecture for equivariant bordism.鈥 听We will show the conjecture is false by finding explicit counterexamples. 听We then build on these techniques to explicitly compute the 2-dimensional G-equivariant unitary and oriented bordism groups for all finite groups G.

This talk is based on joint work with Andr茅s 脕ngel, Carlos Segovia and Bernardo Uribe.