Simplicial volume via foliated simplices and duality
Abstract
Let $M$ be an aspherical oriented closed connected manifold with universal cover $\widetilde{M}\to M$ and let $\Gamma=\pi_1(M)\curvearrowright (X,\mu)$ be a measure preserving action on a standard Borel probability space. We consider singular foliated simplices on the measured foliation $\Gamma\backslash(\widetilde{M}\times X)$ defined by Sauer and we compare the \emph{real singular foliated homology} with classic singular homology. We introduce a notion of \emph{foliated fundamental class} and we prove that its norm coincides with the simplicial volume of $M$. Then we consider the dual cochain complex and define the \emph{singular foliated bounded cohomology}, proving that it is isometrically isomorphic to the measurable bounded cohomology of the action $\Gamma\curvearrowright X$. As a consequence of the duality principle we deduce a vanishing criteria for the simplicial volume in terms of the vanishing of the bounded cohomology of p.m.p actions and of their transverse groupoids.