Counting edges in factorization graphs of numerical semigroup elements

Fuente: arXiv
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Main Authors: Moschetti, Mariah, O'Neill, Christopher
Format: Preprint
Published: 2024
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author Moschetti, Mariah
O'Neill, Christopher
author_facet Moschetti, Mariah
O'Neill, Christopher
contents A numerical semigroup $S$ is an additively-closed set of non-negative integers, and a factorization of an element $n$ of $S$ is an expression of $n$ as a sum of generators of $S$. It is known that for a given numerical semigroup $S$, the number of factorizations of $n$ coincides with a quasipolynomial (that is, a polynomial whose coefficients are periodic functions of $n$). One of the standard methods for computing certain semigroup-theoretic invariants involves assembling a graph or simplicial complex derived from the factorizations of $n$. In this paper, we prove that for two such graphs (which we call the factorization support graph and the trade graph), the number of edges coincides with a quasipolynomial function of $n$, and identify the degree, period, and leading coefficient of each. In the process, we uncover a surprising geometric connection: a combinatorially-assembled cubical complex that is homeomorphic to real projective space.
format Preprint
id arxiv_https___arxiv_org_abs_2401_06912
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Counting edges in factorization graphs of numerical semigroup elements
Moschetti, Mariah
O'Neill, Christopher
Combinatorics
Commutative Algebra
A numerical semigroup $S$ is an additively-closed set of non-negative integers, and a factorization of an element $n$ of $S$ is an expression of $n$ as a sum of generators of $S$. It is known that for a given numerical semigroup $S$, the number of factorizations of $n$ coincides with a quasipolynomial (that is, a polynomial whose coefficients are periodic functions of $n$). One of the standard methods for computing certain semigroup-theoretic invariants involves assembling a graph or simplicial complex derived from the factorizations of $n$. In this paper, we prove that for two such graphs (which we call the factorization support graph and the trade graph), the number of edges coincides with a quasipolynomial function of $n$, and identify the degree, period, and leading coefficient of each. In the process, we uncover a surprising geometric connection: a combinatorially-assembled cubical complex that is homeomorphic to real projective space.
title Counting edges in factorization graphs of numerical semigroup elements
topic Combinatorics
Commutative Algebra
url https://arxiv.org/abs/2401.06912