PURE SUBMODULES AND TORSION FREE IMAGES OF COMPLETELY DECOMPOSABLE TORSION FREE MODULES

ABSTRACT

Prebalanced and precobalanced sequences play an important role in the investigation of Butler Modules. For Butler groups (modules over the integers), they are equivalent conditions. This is not the case for modules over integral domains in general. We investigate conditions when one type of exactness would imply the other. We show that for analytically unramified domains, the equivalence of prebalanced and precobalanced exactness will hold if and only if every maximal ideal has a unique maximal ideal lying over it in the domain's integral closure.

Acknowledgments