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arXiv · 2604.20189

New bounds on Castelnuovo--Mumford regularity of monomial curves and application to sumsets

Abstract

A monomial curve $C$ is defined by a sequence of coprime integers $0 = a_0 < a_1 < \cdots < a_k =: d$. One gap of this sequence is $a_{i+1} - a_i - 1$. Gruson--Lazarsfeld--Peskine bound (1983) says that $reg (C) \le d - k +2$, which is equal to the sum of all gaps plus 2. Lvovsky (1996) showed that it is enough to take the sum of two largest gaps plus 2. In this paper, under some specific conditions, we give several new bounds which are better than Lvovsky's bound. Our method relies on the study of Apery sets and Frobenius numbers. From this we can give new criteria to check the (arithmetically) Cohen--Macaulay and Buchsbaum property of $C$. Algorithms are provided to check these properties as well as to compute $ reg(C)$ and other invariants. We also give an application to study the structure of sumsets.

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BibTeXRIS

Le Tuan Hoa, Doan Quang Tien. 2026-04-22. New bounds on Castelnuovo--Mumford regularity of monomial curves and application to sumsets. https://arxiv.org/abs/2604.20189

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