Nonincreasing depth functions of monomial ideals
Commutative Algebra
2016-12-02 v3
Abstract
Given a nonincreasing function f:Z≥0∖{0}→Z≥0 such that (i) f(k)−f(k+1)≤1 for all k≥1 and (ii) if a=f(1) and b=limk→∞f(k), then ∣f−1(a)∣≤∣f−1(a−1)∣≤⋯≤∣f−1(b+1)∣, a system of generators of a monomial ideal I⊂K[x1,…,xn] for which depthS/Ik=f(k) for all k≥1 is explicitly described. Furthermore, we give a characterization of triplets of integers (n,d,r) with n>0, d≥0 and r>0 with the properties that there exists a monomial ideal I⊂S=K[x1,…,xn] for which limk→∞depthS/Ik=d and dstab(I)=r, where dstab(I) is the smallest integer k0≥1 with depthS/Ik0=depthS/Ik0+1=depthS/Ik0+2=⋯.
Cite
@article{arxiv.1607.07223,
title = {Nonincreasing depth functions of monomial ideals},
author = {Kazunori Matsuda and Tao Suzuki and Akiyoshi Tsuchiya},
journal= {arXiv preprint arXiv:1607.07223},
year = {2016}
}
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7 pages