27 June 2022 to 1 July 2022
University of Geneva
Europe/Zurich timezone

Planar algebras, noncommutativity and hyperfinite subfactors

27 Jun 2022, 11:30
1h
University of Geneva

University of Geneva

Uni Dufour (Auditorium U300 - Charles Rouillier) Rue Général-Dufour 24 Geneva, Geneva 1205 Switzerland

Speaker

Dietmar Bisch

Description

The hyperfinite II_1 factor contains a wealth of subfactors that give rise to many new and fascinating mathematical structures.
Vaughan Jones discovered that the unitary tensor category generated by the standard representation of a subfactor has a planar structure and can be described as what he called a planar algebra''. It is a complete invariant for amenable subfactors by a deep result of Popa. However, generic subfactors are not amenable, and one typically does not know how to distinguish them. I will discuss a notion of asymptotic noncommutativity that can be used to distinguish subfactors with the same planar algebra invariant. I will constructvery noncommutative'' examples from actions of suitable groups on the hyperfinite II$_1$ factor. Moreover, planar algebra techniques lead to new subfactors with Temperley-Lieb-Jones planar algebra.

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