English

Castelnuovo-Mumford regularity of deficiency modules

Commutative Algebra 2009-04-27 v3 Algebraic Geometry

Abstract

Let dNd \in \N and let MM be a finitely generated graded module of dimension d\leq d over a Noetherian homogeneous ring RR with local Artinian base ring R0R_0. Let \beg(M)\beg(M), \gendeg(M)\gendeg(M) and \reg(M)\reg(M) respectively denote the beginning, the generating degree and the Castelnuovo-Mumford regularity of MM. If iN0i \in \N_0 and nZn \in Z, let dMi(n)d^i_M(n) denote the R0R_0-length of the nn-th graded component of the ii-th R+R_+-transform module DR+i(M)D^i_{R_+}(M) of MM and let Ki(M)K^i(M) denote the ii-th deficiency module of MM. Our main result says, that \reg(Ki(M))\reg(K^i(M)) is bounded in terms of \beg(M)\beg(M) and the "diagonal values" dMj(j)d^j_M(-j) with j=0,...,d1j = 0,..., d-1. As an application of this we get a number of further bounding results for \reg(Ki(M))\reg(K^i(M)).

Keywords

Cite

@article{arxiv.0901.0690,
  title  = {Castelnuovo-Mumford regularity of deficiency modules},
  author = {Markus Brodmann and Maryam Jahangiri and Cao Huy Linh},
  journal= {arXiv preprint arXiv:0901.0690},
  year   = {2009}
}

Comments

25 pages, the previous version divided in two parts