A study on v-numbers of $\operatorname{Ext}^i_R(L,M/I^nN)$ and $\operatorname{Tor}_i^R(L,M/I^nN)$

Abstract

Let $R$ be a Noetherian $\mathbb{N}$-graded ring. Assume that $L$ and $M$ are finitely generated $\mathbb{Z}$-graded $R$-module, and $I$ a homogeneous ideal of $R$. Let $N$ be a graded submodule of $M$. Fix $k\in \mathbb{N}$. Denote $H:=\operatorname{Ext}^k_R(L,M)$ (or $\operatorname{Tor}_k^R(L,M)$) and $H_n:=\operatorname{Ext}^k_R(L, M/I^nN)$ (or $\operatorname{Tor}_k^R(L,M/I^nN)$). When $I$ is generated by elements of positive degree, we show that the local $v$-number of $H_n$ either coincides with that of colon submodule $(0:_H I)$ or is a polynomial in $n$ of degree one whose leading coefficient is one of the degrees of the generators of $I$. This extends the main result of Ghosh-Pramanik [J. Algebra 671 (2025), 61-74], where asymptotic linearity was shown under the assumption that $(0:_H I)=0$.