Questioni di suriettività di un morfismo canonico tra due complessi approssimati

Abstract

In this paper, we introduce the concept of i-couple for two ideals, , in a local noetherian ring .This concept is expressed in terms of the structure of (where M is an approximation complex for the double Koszul complex L associated to the system of generators of J), and it generalizes the idea of (d,i)-sequence introduce in [M-R].We study the relationship between the following properties: 1) is an i- couple of ideals in R; 2) is an i- couple of ideals in , more generally, in , .So we get some sufficient conditions for the "ascendent" and "descendent" properties of the i –couple.In particular, we study the surjectivity of the natural morphism(Error rendering LaTeX formula), since the surjectivity of is a sufficient condition for the "descendent" property of the i - ouple from R to .