2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/67310We prove several duality theorems for the Galois and etale cohomology of 1-motives defined over local and global fields and establish a 12-term Poitou-Tate type exact sequence. The results give a common generalisation and sharpening of well-known theorems by Tate on abelian varieties as well as results by Tate/Nakayama and Kottwitz on algebraic tori.44 pages, LaTeX, final version. Section 5 substantially rewrittenNumber TheoryAlgebraic Geometry14G25, 14G20, 14K15text