The equations of Rees algebras of equimultiple ideals of deviation one

Abstract

We describe the equations of the Rees algebra R(I) of an equimultiple ideal I of deviation one, provided that I has a reduction J generated by a regular sequence and such that the initial forms of the elements of this sequence, except possibly the last one, are also a regular sequence in the associated graded ring of I. In particular, we prove that there is a single equation of top degree in a minimal generating set of the ideal of equations of R(I) and we relate this degree to the reduction number, recovering several known results in the context.