Abstract

Let △ be a multiplicatively closed set of finitely generated nonzero ideals of a ring R. Then the concept of a △ -reduction of an R -submodule D of an R -module A is introduced and several basic properties of such reductions are established. Among these are that a minimal △ -reduction B of D exists and that every minimal basis of B can be extended to a minimal basis of all R -submodules between B and D, when R is local and A is a finite R -module. Then, as an application, △ -reductions B of a submodule C with property (*) are introduced, characterized, and shown to be quite plentiful. Here, (*) means that (R ,M) is a local ring of altitude at least one, that △ = {Mn ; n ≥ 0} and that if D ⊆ E are R -submodules between B and C, then every minimal basis of D can be extended to a minimal basis of E.