Geometry Seminar

Date: November 1, 2021

Time: 3:00PM - 4:00PM

Location: BLOC 302

Speaker: John Berman, University of Massachusetts Amherst

Title: Measuring Ramification with Topological Hochschild Homology

Abstract: Topological Hochschild homology (THH) has recently been popular as an approximation to algebraic K-theory, but it is also a measure of ramification in the sense of number theory. I will survey the interaction between THH and ramification / etale extensions, along with some surprising connections to classical algebraic topology. This will culminate in a new computation of THH of any ring of integers R, suggesting the philosophy: Spec(R) -> Spec(Z) is one point away from being etale.