The Witt group of braided fusion categories


Dmitri Nikshych


University of New Hampshire


Wed, 31/05/2017 -
2:00pm to 3:00pm


RC-4082, The Red Centre, UNSW


A classical theorem of Joyal and Street establishes an equivalence between braided categorical groups and quadratic forms.  This  brings an important geometric insight into the theory of braided fusion categories: one can  treat them as non-commutative geometric objects. From this point of view the Drinfeld centers correspond to hyperbolic quadratic forms. We use this observation to define a categorical analogue of the classical Witt group of quadratic forms. It turns out that the categorical Witt group W is no longer a torsion group. We discuss the structure of W and its generalizations: the super and equivariant categorical Witt groups. This talk is based on joint works with Alexei Davydov, Victor Ostrik, and Michael Mueger.

The talk will also be streamed here.

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