Algebra/Topology seminar – University of Copenhagen

Algebra/Topology seminar

Elden Elmanto (Northwestern), Infinite Loop Spaces in Algebraic Geometry

Abstract: A classical theorem in modern homotopy theory states that functors from finite pointed sets to spaces satisfying certain conditions model infinite loop spaces (Segal 1974). This theorem offers a recognition principle for infinite loop spaces. An analogous theorem for Morel-Voevodsky's motivic homotopy theory has been sought for since its inception. 

In joint work with Marc Hoyois, Adeel Khan, Vladimir Sosnilo and Maria Yakerson, we provide such a theorem. The category of finite pointed sets is replaced by a category where the objects are smooth schemes and the maps are spans whose "left legs" are finite syntomic maps equipped with a K​-theoretic trivialization of its contangent complex. I will explain what this means, how it is not so different from finite pointed sets and why it was a natural guess. In particular, I will explain some of the requisite algebraic geometry.

Time permitting, I will also provide:

1) an explicit model for the motivic sphere spectrum as a torsor over a Hilbert scheme and, 

2) a model for all motivic Eilenberg-Maclane spaces as simplicial ind-smooth schemes.