No CrossRef data available.
Published online by Cambridge University Press: 17 August 2017
We associate with every étale groupoid
$\mathfrak{G}$ two normal subgroups
$\mathsf{S}(\mathfrak{G})$ and
$\mathsf{A}(\mathfrak{G})$ of the topological full group of
$\mathfrak{G}$, which are analogs of the symmetric and alternating groups. We prove that if
$\mathfrak{G}$ is a minimal groupoid of germs (e.g., of a group action), then
$\mathsf{A}(\mathfrak{G})$ is simple and is contained in every non-trivial normal subgroup of the full group. We show that if
$\mathfrak{G}$ is expansive (e.g., is the groupoid of germs of an expansive action of a group), then
$\mathsf{A}(\mathfrak{G})$ is finitely generated. We also show that
$\mathsf{S}(\mathfrak{G})/\mathsf{A}(\mathfrak{G})$ is a quotient of
$H_{0}(\mathfrak{G},\mathbb{Z}/2\mathbb{Z})$.