Algebraic Geometry Seminar

Title: Tate extensions in the cohomology of a Baily-Borel compactification
Speaker: Eduard Looijenga
Speaker Info: Yau Mathematical Sciences Centre, Tsinghua University, Beijing
Brief Description:

An automorphic vector bundle on a Shimura variety will in general not extend to as a bundle to its Baily-Borel compactification. Yet Goresky and Pardon showed that the Chern classes of such a bundle do so in a natural manner. They wondered whether these classes lie in rational cohomology. We show that these extensions have a natural description in the setting of mixed Hodge theory and may not lie in rational cohomology. We apply this to the stable cohomology of the Baily-Borel compactification of the ppav's and show that they yield the basic nontrivial Tate extensions.
Date: Wednesday, February 08, 2017
Time: 4:00pm
Where: Lunt 105
Contact Person: Ezra Getzler
Contact email: getzler@northwestern.edu
Contact Phone:
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