2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/117832Gabber's Theorem claims that the singular support of a D-module is involutive. We show how to give a conceptually clear proof of this in the context of Hochschild Homology and Cohomology of abelian categories.LaTeX2e, 13 pages. Minor changes: slightly rewrote the introduction to reflect better the history of Gabber's TheoremAlgebraic GeometrySymplectic Geometrytext