Specialization of modules over a local ring

Abstract

This paper is a continuation of an earlier paper of the authors on the probem of specializations of modules. The aim here is to define specialisations of finitely generated modules over local rings of the form k(u)[X]_P, where u is a family of indeterminates over a field k. The definition depends on the associated primes of the specialisation of the prime ideal P by the substitution of u to elements of k. As in the non-local case, the introduced specializations preserve basic properties and operations on modules.In particular, annihilators of local cohomology modules commute with specializations. As a consequence, Cohen-Macaulayness and Buchsbaumness are preserved by almost al substitutions. The paper also studies the non-Cohen-Macaulay locus and the singular locus of specializations of factor rings of k(u)[X]_P.