##### Department of Mathematics,

University of California San Diego

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### Algebraic Geometry Seminar

## Alexander Perry

#### Columbia University

## Deformation and derived equivalent but non-birational Calabi-Yau threefolds

##### Abstract:

I will construct a pair of Calabi-Yau threefolds which are deformation and derived equivalent, but not birationally equivalent. I will explain how this gives a counterexample to the birational Torelli problem for Calabi-Yau threefolds, as well as new examples of zero divisors in the Grothendieck ring of varieties. This is joint work with Lev Borisov and Andrei Caldararu.

Host: David Stapleton

### May 25, 2018

### 2:30 PM

### AP&M 5829

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