2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/75316Given an abelian category with arbitrary products, arbitrary coproducts, and a generator, we show that the closed subspaces (in the sense of A. L. Rosenberg) are parameterized by a suitably defined poset of ideals in the generator. In particular, the collection of closed subspaces is itself a small poset.4 pages; AMS-TeX; to appear in Proc. Amer. Math. SocAlgebraic GeometryRings and Algebras14A22text