2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/59188We define abelian extensions of algebras in congruence-modular varieties. The theory is sufficiently general that it includes, in a natural way, extensions of R-modules for a ring R. We also define a cohomology theory, which we call clone cohomology, such that the cohomology group in dimension one is the group of equivalence classes of extensions.30 pagesRings and Algebras18G60 (Primary); 08B99 (Secondary)text