On the Fundamental Group of Type II$

2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/65485We present here a shorter version of the proof of a result from our paper ``On a class of type II$_1$ factors with Betti numbers invariants'', showing that the von Neumann factor associated with the group $\Bbb Z^2 \rtimes SL(2, \Bbb Z)$ has trivial fundamental group.Operator AlgebrasGroup Theory46L (primary); 20G, 22D (secondary)On the Fundamental Group of Type II$_1$ Factorstext