Numerical semigroups via projections and via quotients

Fuente: arXiv
Saved in:
Bibliographic Details
Main Authors: Bogart, Tristram, O'Neill, Christopher, Woods, Kevin
Format: Preprint
Published: 2023
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866917638630801408
author Bogart, Tristram
O'Neill, Christopher
Woods, Kevin
author_facet Bogart, Tristram
O'Neill, Christopher
Woods, Kevin
contents We examine two natural operations to create numerical semigroups. We say that a numerical semigroup $\mathcal{S}$ is $k$-normalescent if it is the projection of the set of integer points in a $k$-dimensional polyhedral cone, and we say that $\mathcal{S}$ is a $k$-quotient if it is the quotient of a numerical semigroup with $k$ generators. We prove that all $k$-quotients are $k$-normalescent, and although the converse is false in general, we prove that the projection of the set of integer points in a cone with $k$ extreme rays (possibly lying in a dimension smaller than $k$) is a $k$-quotient. The discrete geometric perspective of studying cones is useful for studying $k$-quotients: in particular, we use it to prove that the sum of a $k_1$-quotient and a $k_2$-quotient is a $(k_1+k_2)$-quotient. In addition, we prove several results about when a numerical semigroup is not $k$-normalescent.
format Preprint
id arxiv_https___arxiv_org_abs_2306_11564
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Numerical semigroups via projections and via quotients
Bogart, Tristram
O'Neill, Christopher
Woods, Kevin
Commutative Algebra
Combinatorics
We examine two natural operations to create numerical semigroups. We say that a numerical semigroup $\mathcal{S}$ is $k$-normalescent if it is the projection of the set of integer points in a $k$-dimensional polyhedral cone, and we say that $\mathcal{S}$ is a $k$-quotient if it is the quotient of a numerical semigroup with $k$ generators. We prove that all $k$-quotients are $k$-normalescent, and although the converse is false in general, we prove that the projection of the set of integer points in a cone with $k$ extreme rays (possibly lying in a dimension smaller than $k$) is a $k$-quotient. The discrete geometric perspective of studying cones is useful for studying $k$-quotients: in particular, we use it to prove that the sum of a $k_1$-quotient and a $k_2$-quotient is a $(k_1+k_2)$-quotient. In addition, we prove several results about when a numerical semigroup is not $k$-normalescent.
title Numerical semigroups via projections and via quotients
topic Commutative Algebra
Combinatorics
url https://arxiv.org/abs/2306.11564