I. García-Marco | Searcharxiv

arXiv2026

A note on strong affine semigroups

This work introduces and studies strong affine semigroups, extending the notion of strong numerical semigroups to the higher-dimensional setting. We show that non-numerical strong affine semigroups present structural differences with respect to strong numerical semigroups. Special attention is devoted to strong $\mathcal C$-semigroups. We prove that the family of strong $\mathcal C$-semigroups with a given set of multiplicities $E$ admits a maximal element and has a tree structure. We characterize when this family is finite and provide an algorithm to compute all such semigroups up to a fixed genus. We also introduce the notion of special strong affine semigroups and obtain refined versions of several previous results. Finally, we study toric ideals arising from strong affine semigroups, determining their indispensable monomials and Betti elements for several families.

math.AC↗

arXiv2014

Complete intersections in certain affine and projective monomial curves

Let $k$ be an arbitrary field, the purpose of this work is to provide families of positive integers $\mathcal{A} = \{d_1,\ldots,d_n\}$ such that either the toric ideal $I_{\mathcal A}$ of the affine monomial curve $\mathcal C = \{(t^{d_1},\ldots,\,t^{d_n}) \ | \ t \in k\} \subset \mathbb{A}_k^n$ or the toric ideal $I_{\mathcal A^{\star}}$ of its projective closure ${\mathcal C^{\star}} \subset \mathbb{P}_k^n$ is a complete intersection. More precisely, we characterize the complete intersection property for $I_{\mathcal A}$ and for $I_{\mathcal A^{\star}}$ when: (a) $\mathcal{A}$ is a generalized arithmetic sequence, (b) $\mathcal{A} \setminus \{d_n\}$ is a generalized arithmetic sequence and $d_n \in \mathbb{Z}^+$, (c) $\mathcal{A}$ consists of certain terms of the $(p,q)$-Fibonacci sequence, and (d) $\mathcal{A}$ consists of certain terms of the $(p,q)$-Lucas sequence. The results in this paper arise as consequences of those in Bermejo et al. [J. Symb. Comput. 42 (2007)], Bermejo and Garc\'ıa-Marco [J. Symb. Comput. (2014), to appear] and some new results regarding the toric ideal of the curve.

math.AC↗