Bounds on the Castelnuovo-Mumford Regularity in dimension two (2404.01684v1)

Abstract: Consider a Cohen-Macaulay local ring $(R,\mathfrak m)$ with dimension $d\geq 2$, and let $I \subseteq R$ be an $\mathfrak m$-primary ideal. Denote $r_{J}(I)$ as the reduction number of $I$ with respect to a minimal reduction $J$ of $I$, and $\rho(I)$ as the stability index of the Ratliff-Rush filtration with respect to $I$. In this paper, we derive a bound on $\rho(I)$ in terms of the Hilbert coefficients and $r_{J}(I)$. In the case of two-dimensional Cohen-Macaulay local rings, the established bound on $\rho(I)$ consequently leads to a bound on the Castelnuovo-Mumford regularity of the associated graded ring of $I$.