Amalgamated Free Products of $w$-Rigid Factors and Calculation of their Symmetry Groups

A. Ioana, J. Peterson, S. Popa

We consider amalgamated free product II${}_1$ factors $M=M_1{\ast }_B{M}_2{\ast }_B...$ and use ``deformation/rigidity'' and ``intertwining'' techniques to prove that any relatively rigid vo…