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Numerical semigroups have been extensively studied throughout the literature, and many of their invariants have been characterized. In this work, we generalize some of the most important results about symmetry, pseudo-symmetry, or…

For a semigroup $S$, the covering number of $S$ with respect to semigroups, $\sigma_s(S)$, is the minimum number of proper subsemigroups of $S$ whose union is $S$. This article investigates covering numbers of semigroups and analogously…

Group Theory · Mathematics 2020-02-12 Casey Donoven , Luise-Charlotte Kappe

We establish a one-to-one correspondence between numerical semigroups of genus $g$ and almost symmetric numerical semigroups with Frobenius number $F$ and type $F-2g$, provided that $F$ is greater than $4g-1$.

Group Theory · Mathematics 2021-06-30 Pedro A. Garcia-Sanchez , Ignacio Ojeda

A numerical semigroup is a sub-semigroup of the natural numbers that has a finite complement. The size of its complement is called the genus and the largest number in the complement is called its Frobenius number. We consider the set of…

Combinatorics · Mathematics 2020-08-10 Deepesh Singhal

Let $\mathcal{C}\subseteq \mathbb{N}^p$ be an integer cone. A $\mathcal{C}$-semigroup $S\subseteq \mathcal{C}$ is an affine semigroup such that the set $\mathcal{C}\setminus S$ is finite. Such $\mathcal{C}$-semigroups are central to our…

Commutative Algebra · Mathematics 2024-09-11 J. C. Rosales , R. Tapia-Ramos , A. Vigneron-Tenorio

Let $S,T$ be two numerical semigroups. We study when $S$ is one half of $T$, with $T$ almost symmetric. If we assume that the type of $T$, $t(T)$, is odd, then for any $S$ there exist infinitely many such $T$ and we prove that $1 \leq t(T)…

Commutative Algebra · Mathematics 2014-04-22 Francesco Strazzanti

A numerical semigroup is a subset of N containing 0, closed under addition and with finite complement in N. An important example of numerical semigroup is given by the Weierstrass semigroup at one point of a curve. In the theory of…

Number Theory · Mathematics 2017-06-30 Maria Bras-Amorós

Let a, k, h, c be positive integers and d a non zero integer. Recall that a numerical generalized almost arithmetic semigroup S is a semigroup minimally generated by relatively prime positive integers a, ha + d, ha + 2d, . . . , ha + kd, c,…

Commutative Algebra · Mathematics 2026-01-13 Marcel Morales , Nguyen Thi Dung

In this paper we compute the Frobenius number of certain {\em Fibonacci numerical semigroups}, that is, numerical semigroups generated by a set of Fibonacci numbers, in terms of Fibonacci numbers.

Combinatorics · Mathematics 2007-05-23 J. M. Marin , J. Ramirez Alfonsin , M. P. Revuelta

Consider a sequence of positive integers of the form $ca^n-d$, $n\geq 1$, where $a, c$ and $d$ are positive integers, $a>1$. For each $n\geq 1$, let $S_n$ be the submonoid of $\mathbb N$ generated by $\mathbf s_j=ca^{n+j}-d$, with…

Number Theory · Mathematics 2023-01-25 Fabián Arias , Jerson Borja

We define the concentration of a numerical semigroup $S$ as $\mathsf{C}(S)=\max \left\{\text{next}_S(s)-s ~|~ s\in S \backslash \{0\}\right\}$ wherein $\text{next}_S(s)=\min\left\{x \in S ~|~ s<x\right\}$. In this paper, we study the class…

Commutative Algebra · Mathematics 2021-04-01 José C. Rosales , M. B. Branco , Márcio A. Traesel

In this paper we introduce the notion of extension of a numerical semigroup. We provide a characterization of the numerical semigroups whose extensions are all arithmetic and we give an algorithm for the computation of the whole set of…

Commutative Algebra · Mathematics 2020-03-31 Ignacio Ojeda , José Carlos Rosales

Let $a,b$ be positive integers. In this note, we study the numerical semigroup $H=\left<a,a+1,b\right>$ and and the associated numerical semigroup ring $R=k[[H]]$. Under the certain conditions, we provide explicit formulas for the Frobenius…

Group Theory · Mathematics 2026-01-30 Do Van Kien , Pham Hung Quy

For $p>0$ a small parameter, let $\mathcal A \subseteq \mathbb{Z}_{>0}$ be a random subset where each positive integer is included independently with probability $p$. We show that, with high probability (as $p \to 0$), the numerical…

Combinatorics · Mathematics 2025-09-17 Noah Kravitz , Santiago Morales , Carl Schildkraut

In 1990, Backelin showed that the number of numerical semigroups with Frobenius number $f$ approaches $C_i \cdot 2^{f/2}$ for constants $C_0$ and $C_1$ depending on the parity of $f$. In this paper, we generalize this result to semigroups…

Combinatorics · Mathematics 2023-12-27 Sean Li

An $\mathcal{A}$-semigroup is a numerical semigroup without consecutive small elements. This work generalizes this concept to finite-complement submonoids of an affine cone $\mathcal{C}$. We develop algorithmic procedures to compute all…

Commutative Algebra · Mathematics 2025-06-23 J. C. Rosales , R. Tapia-Ramos , A. Vigneron-Tenorio

We present a procedure to enumerate the whole set of numerical semigroups with a given Frobenius number F, S(F). The methodology is based on the construction of a partition of S(F) by a congruence relation. We identify exactly one…

Commutative Algebra · Mathematics 2011-05-26 V. Blanco , J. C. Rosales

We introduce the concept of homogeneous numerical semigroups and show that all homogeneous numerical semigroups with Cohen-Macaulay tangent cones are of homogeneous type. In embedding dimension three, we classify all numerical semigroups of…

Commutative Algebra · Mathematics 2018-04-20 Raheleh Jafari , Santiago Zarzuela Armengou

In this work we present a new class of numerical semigroups called GSI-semigroups. We see the relations between them and others families of semigroups and we give explicitly their set of gaps. Moreover, an algorithm to obtain all the…

Commutative Algebra · Mathematics 2022-07-28 E. R. García Barroso , J. I. García-García , A. Vigneron-Tenorio

In this paper we present a new approach to construct the set of numerical semigroups with a fixed genus. Our methodology is based on the construction of the set of numerical semigroups with fixed Frobenius number and genus. An equivalence…

Combinatorics · Mathematics 2011-06-09 V. Blanco , J. C. Rosales