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Controlled Mather Thurston theorems

Geometry/Topology

Speaker: Mike Freedman, Microsoft Station Q
Location: Zoom
Start time: Tue, Mar 2 2021, 1:10PM

Description

In the work of Milnor Wood and in the Mather Thurston theorem, we encounter flat connections in surprising places. The surprise is comes from the close encounter with obstructions ( that would prevent theses connections) from Godbillion-Vey and Chern-Weil. The escape from contradiction is that the constructions have larger structure groups than needed to define the obstructions. I will describe some techniques for constructing flat connections with additional control, and briefly touch on the physics motivation for achieving this control.