Algebraic Geometry Seminar
Non-Abelian Lefschetz Hyperplane Theorems
Speaker: Daniel Litt, Columbia University
Location: Warren Weaver Hall 1314
Date: Tuesday, September 29, 2015, 3:30 p.m.
How are the properties of a variety X related to those of an ample divisor D in X? Classical Lefschetz hyperplane theorems answer this question by comparing the cohomology or homotopy type of X to that of D. I'll describe new results, encapsulating some of these older Lefschetz theorems, which compare F(X) to F(D) where F is any functor which is representable in a suitable sense. While the main results are in characteristic zero, the method of proof passes through positive characteristic.