English

Quasi-finite modules and asymptotic prime divisors

Commutative Algebra 2013-01-30 v1

Abstract

Let AA be a Noetherian ring, JAJ\subseteq A an ideal and CC a finitely generated AA-module. In this note we would like to prove the following statement. Let {In}n0\{I_n\}_{n\geq 0} be a collection of ideals satisfying : (i) InJnI_n\supseteq J^n, for all nn, (ii) JsIsIr+sJ^s\cdot I_s \subseteq I_{r+s}, for all r,s0r,s\geq 0 and (iii) InImI_n\subseteq I_m, whenever mnm\leq n. Then \AssA(InC/JnC)\Ass_A(I_nC/J^nC) is independent of nn, for nn sufficiently large. Note that the set of prime ideals n1\AssA(InC/JnC)\cup_{n\geq 1} \Ass_A(I_nC/J^nC) is finite, so the issue at hand is the realization that the primes in \AssA(InC/JnC)\Ass_A(I_nC/J^nC) \textit{do not} behave periodically, as one might have expected, say if n0In\bigoplus _{n\geq 0}I_n were a Noetherian AA-algebra generated in degrees greater than one. We also give a multigraded version of our results.

Keywords

Cite

@article{arxiv.1301.6886,
  title  = {Quasi-finite modules and asymptotic prime divisors},
  author = {Daniel Katz and Tony J. Puthenpurakal},
  journal= {arXiv preprint arXiv:1301.6886},
  year   = {2013}
}

Comments

to appear in Journal of Algebra