Conceptual

Cohomology of Ample Groupoids via Flat Resolutions

A cochain-complex definition of the cohomology of an ample (etale, locally compact totally disconnected) groupoid: build a flat resolution defining the groupoid's homology with integer coefficients, then take cohomology with values in a groupoid module. The construction is proved to coincide with the earlier continuous-cocycle cohomology, hence is invariant under Morita equivalence; it yields an exact sequence for skew products by an integer-valued cocycle and explicit computations for AF-groupoids and certain action groupoids.