Event time:
Thursday, November 12, 2015 - 10:00am to 11:00am
Location:
LOM 214
Speaker:
Daniel Litt
Speaker affiliation:
Columbia University
Event description:
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.