The planar algebra of diagonal subfactors

Abstract

There is a natural construction which associates to a finitely generated, countable, discrete group $G$ and a 3-cocycle $\omega$ of $G$ an inclusion of II${}_1$ factors, the so-called diagonal subfactors (with cocycle). In the case when the cocycle is trivial these subfactors are well studied and their standard invariant (or planar algebra) is known. We give a description of the planar algebra of these subfactors when a cocycle is present. The action of Jones' planar operad involves the 3-cocycle $\omega$ explicitly and some interesting identities for 3-cocycles appear when naturality of the action is verified.

21 pages, 7 figures

References in corpus (1)

• The planar algebra of group-type subfactors