Conjugate Pairs of Subfactors and Entropy for Automorphisms

Abstract

Based on the fact that, for a subfactor $N$ of a II${}_1$ factor $M,$ the first non-trivial Jones index is 2 and then $M$ is decomposed as the crossed product of $N$ by an outer action of ${\mathbb{Z}}_2,$ we study pairs $\{N,uN{u}^{\ast }\}$ from a view point of entropy for two subalgebras of $M$ with a connection to the entropy for automorphisms, where the inclusion of II${}_1$ factors $N\subset M$ is given as $M$ is the crossed product of $N$ by a finite group of outer automorphisms and $u$ is a unitary in $M.$

20 pages