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Main Authors: Cyrusian, Sogol, Domat, Alex, O'Neill, Christopher, Ponomarenko, Vadim, Ren, Eric, Ward, Mayla
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2503.12241
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author Cyrusian, Sogol
Domat, Alex
O'Neill, Christopher
Ponomarenko, Vadim
Ren, Eric
Ward, Mayla
author_facet Cyrusian, Sogol
Domat, Alex
O'Neill, Christopher
Ponomarenko, Vadim
Ren, Eric
Ward, Mayla
contents A numerical semigroup $S$ is a cofinite, additively-closed subset of $\mathbb Z_{\ge 0}$ that contains 0, and a factorization of $x \in S$ is a $k$-tuple $z = (z_1, \ldots, z_k)$ where $x = z_1a_1 + \cdots + z_ka_k$ expresses $x$ as a sum of generators of $S = \langle a_1, \ldots, a_k \rangle$. Much~of the study of non-unique factorization centers on factorization length $z_1 + \cdots + z_k$, which coincies with the $\ell_1$-norm of $z$ as the $k$-tuple. In this paper, we study the $\ell_\infty$-norm and $\ell_0$-norm of factorizations, viewed as alternative notions of length, with particular focus on the generalizations $Δ_\infty(x)$ and $Δ_0(x)$ of the delta set $Δ(x)$ from classical factorization length. We prove that the $\infty$-delta set $Δ_\infty(x)$ is eventually periodic as a function of $x \in S$, classify $Δ_\infty(S)$ and the 0-delta set $Δ_0(S)$ for several well-studied families of numerical semigroups, and identify families of numerical semigroups demonstrating $Δ_\infty(S)$ and $Δ_0(S)$ can be arbitrarily long intervals and can avoid arbitrarily long subintervals.
format Preprint
id arxiv_https___arxiv_org_abs_2503_12241
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On numerical semigroup elements and the $\ell_0$- and $\ell_\infty$-norms of their factorizations
Cyrusian, Sogol
Domat, Alex
O'Neill, Christopher
Ponomarenko, Vadim
Ren, Eric
Ward, Mayla
Commutative Algebra
A numerical semigroup $S$ is a cofinite, additively-closed subset of $\mathbb Z_{\ge 0}$ that contains 0, and a factorization of $x \in S$ is a $k$-tuple $z = (z_1, \ldots, z_k)$ where $x = z_1a_1 + \cdots + z_ka_k$ expresses $x$ as a sum of generators of $S = \langle a_1, \ldots, a_k \rangle$. Much~of the study of non-unique factorization centers on factorization length $z_1 + \cdots + z_k$, which coincies with the $\ell_1$-norm of $z$ as the $k$-tuple. In this paper, we study the $\ell_\infty$-norm and $\ell_0$-norm of factorizations, viewed as alternative notions of length, with particular focus on the generalizations $Δ_\infty(x)$ and $Δ_0(x)$ of the delta set $Δ(x)$ from classical factorization length. We prove that the $\infty$-delta set $Δ_\infty(x)$ is eventually periodic as a function of $x \in S$, classify $Δ_\infty(S)$ and the 0-delta set $Δ_0(S)$ for several well-studied families of numerical semigroups, and identify families of numerical semigroups demonstrating $Δ_\infty(S)$ and $Δ_0(S)$ can be arbitrarily long intervals and can avoid arbitrarily long subintervals.
title On numerical semigroup elements and the $\ell_0$- and $\ell_\infty$-norms of their factorizations
topic Commutative Algebra
url https://arxiv.org/abs/2503.12241