2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/62419In this paper we give bounds on the Castelnuovo-Mumford regularity of products of ideals and ideal sheaves. In particular, we show that the regularity of a product of ideals is bounded by the sum of the regularities of its factors if the corresponding schemes intersect in a finite set of points. We also show how approximations of sheaves can be used to bound the regularity of an arrangement of two-planes in projective space.9 pages, Minor additions to introduction, references added, typos corrected, minor change in exposition of main theoremAlgebraic GeometryCommutative AlgebraCombinatorics13D02; 52C35text