4 papers
Partial actions of free groups and groupoid homology
Benjamin Steinberg
We give a length one projective resolution of the trivial module for the groupoid of a semi-saturated partial action (in the sense of Exel) of a free group on a compact Hausdorff a…
A short proof of a bound on the size of finite irreducible semigroups of rational matrices
Benjamin Steinberg
I give a short proof of a recent result due to Kiefer and Ryzhikov showing that a finite irreducible semigroup of matrices has cardinality at most .
Realizing wedges of Moore spaces as classifying spaces of finite semigroups
Aris Martinian, Benjamin Steinberg
Fiedorowicz suggested that it was likely that every finite simply connected CW complex is homotopy equivalent to the classifying space of a finite semigroup. We prove that every fi…
On von Neumann regularity of ample groupoid algebras
Benjamin Steinberg, Daniel W. van Wyk
We completely characterize when the algebra of an ample groupoid with coefficients in an arbitrary unital ring is von Neumann regular and, more generally, when the algebra of a gra…