Adeel Khan (Regensburg): A criterion for descent by blow-ups

Unlike most cohomology theories in algebraic geometry, algebraic K-theory does not satisfy descent with respect to arbitrary blow-up squares. We explain why the only obstruction is the failure of the Mayer-Vietoris property for unions of closed subschemes. Since this obstruction vanishes after forcing A1-homotopy invariance, this gives a direct new proof of Cisinski's theorem that homotopy K-theory does satisfy cdh descent.

Published Apr. 23, 2019 5:32 PM - Last modified Apr. 23, 2019 5:32 PM