Comparison of stability indices of powers of graded ideals

TL;DR

This paper compares two stability indices of powers of graded ideals, establishing specific equalities in low-dimensional rings and constructing ideals with prescribed stability indices in higher dimensions.

Contribution

It provides new results relating the index of ass-stability and v-stability for graded ideals, including explicit constructions in higher-dimensional polynomial rings.

Findings

stab(I)=1 for any graded ideal in a 2D polynomial ring

stab(I) can be any positive integer in this setting

Constructed ideals in higher dimensions with prescribed stability indices

Abstract

In this paper, we compare the index of ass-stability $\text{astab}(I)$ and the index of $\text{v}$-stability $\text{vstab}(I)$ of powers of a graded ideal $I$. We prove that $\text{astab}(I)=1\le\text{vstab}(I)$ for any graded ideal $I$ in a 2-dimensional polynomial ring, and that $\text{vstab}(I)$ can be any positive integer in this situation. Moreover, given any integers $a,b\ge1$, we construct a graded ideal $I$ in a $3(a+1)$-dimensional polynomial ring such that $(\text{astab}(I),\text{vstab}(I))=(a,b)$.