Hopf invariants, rational homotopy theory, and physical integrals.

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Event details

Date 02.02.2016
Hour 10:1511:30
Speaker Dev Sinha
Location
MA110
Category Conferences - Seminars
We discuss a basic question in algebraic topology: given two maps f,g : X —> Y, how can we tell whether or not they are homotopic?  One condition is that f and g should pull back cohomology in the same way.  But even when X is a sphere, this is far from sufficient.  In relatively recent work, Ben Walter and I resolve this question when X is a sphere and Y is simply connected, rationally (that is, up to then multiplying f and g by some non-zero integer).  We do so by giving explicit integrals, generalizing Whitehead’s integral formula for the Hopf invariant, which has been cited regularly in the physics literature.  These integrals are a concrete manifestation of Koszul duality.   These integrals are also similar to integrals developed by Cattaneo and Mnev in the context of Chern-Simons theory.  We speculate on the connection, as well as potential connection with L_\infty models for rational homotopy theory.

Practical information

  • Informed public
  • Free

Organizer

  • Magdalena Kedziorek

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