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We study finite semigroups of $n \times n$ matrices with rational entries. Such semigroups provide a rich generalization of transition monoids of unambiguous (and, in particular, deterministic) finite automata. In this paper we determine…

Formal Languages and Automata Theory · Computer Science 2026-01-06 Stefan Kiefer , Andrew Ryzhikov

We present a new algorithm to explore or count the numerical semigroups of a given genus which uses the unleaved version of the tree of numerical semigroups. In the unleaved tree there are no leaves rather than the ones at depth equal to…

Combinatorics · Mathematics 2026-05-13 Maria Bras-Amorós

We provide a new upper bound for the length for the shortest non-trivial element in the lower central series $\gamma_n(\mathbb{F}_2)$ of the free group on two generators. We prove that it has an asymptotic behaviour of the form…

Group Theory · Mathematics 2016-11-01 Abdelrhman Elkasapy

We study suitable parameters and relations in a numerical semigroup S. When S is the Weierstrass semigroup at a rational point P of a projective curve C, we evaluate the Feng-Rao order bound of the associated family of Goppa codes. Further…

Information Theory · Computer Science 2010-02-10 Anna Oneto , Grazia Tamone

Galluccio--Loebl and Tesler showed that the perfect-matching polynomial of a graph embedded in an orientable surface of genus $g$ can be written as a linear combination of at most $4^g$ Pfaffians. We show that, in general, exponentially…

Combinatorics · Mathematics 2026-05-21 Priyanshu Pant , Ranveer Singh

This paper aims to contribute to validate, for numerical semigroups of reasonably large genus, the so-called Conjecture of Wilf. There is no counter-example for the conjecture among the over 3*10^{10} numerical semigroups of genus up to 60,…

Combinatorics · Mathematics 2019-10-29 Manuel Delgado

We introduce the quasi-ordinarization transform of a numerical semigroup. This transform will allow to organize all the semigroups of a given genus in a forest rooted at all quasi-ordinary semigroups with the given genus. This construction…

Combinatorics · Mathematics 2021-06-16 Maria Bras-Amorós , Hebert Pérez-Rosés , José Miguel Serradilla-Merinero

We continue our study of exponent semigroups of rational matrices. Our main result is that the matricial dimension of a numerical semigroup is at most its multiplicity (the least generator), greatly improving upon the previous upper bound…

Combinatorics · Mathematics 2024-07-23 Arsh Chhabra , Stephan Ramon Garcia , Christopher O'Neill

In this work we introduce the notion of almost-symmetry for generalized numerical semigroups. In addition to the main properties occurring in this new class, we present several characterizations for its elements. In particular we show that…

Combinatorics · Mathematics 2020-12-29 Carmelo Cisto , Wanderson Tenório

Let $S\neq\mathbb N$ be a numerical semigroup with Frobenius number $f$, genus $g$ and embedding dimension $e$. In 1978 Wilf asked the question, whether $\frac{f+1-g}{f+1}\geq\frac1e$. As is well known, this holds in the cases $e=2$ and…

Number Theory · Mathematics 2021-08-10 Michael Hellus , Anton Rechenauer , Rolf Waldi

In this paper, we prove that the numerical-semigroup-gap counting problem is #NP-complete as a main theorem. A numerical semigroup is an additive semigroup over the set of all nonnegative integers. A gap of a numerical semigroup is defined…

Computational Complexity · Computer Science 2017-01-05 Shunichi Matsubara

The \emph{genus} $\mathrm{g}(G)$ of a graph $G$ is the minimum $g$ such that $G$ has an embedding on the orientable surface $M_g$ of genus $g$. A drawing of a graph on a surface is \emph{independently even} if every pair of nonadjacent…

Combinatorics · Mathematics 2019-03-21 Radoslav Fulek , Jan Kynčl

A numerical semigroup is an additive subsemigroup of the non-negative integers. In this paper, we consider parametrized families of numerical semigroups of the form $P_n = \langle f_1(n), \ldots, f_k(n) \rangle$ for polynomial functions…

Commutative Algebra · Mathematics 2020-05-20 Franklin Kerstetter , Christopher O'Neill

For any positive integer $q\geq 2$ and any real number $\delta\in(0,1)$, let $\alpha_q(n,\delta n)$ denote the maximum size of a subset of $\mathbb{Z}_q^n$ with minimum Hamming distance at least $\delta n$, where…

Combinatorics · Mathematics 2024-03-22 Xue-Bin Liang

Let $A \subset {\mathbb Z}$ be a finite subset. We denote by $\mathcal{B}(A)$ the set of all integers $n \ge 2$ such that $|nA| > (2n-1)(|A|-1)$, where $nA=A+\cdots+A$ denotes the $n$-fold sumset of $A$. The motivation to consider…

Combinatorics · Mathematics 2020-11-25 S. Eliahou , J. I. García-García , D. Marín-Aragón , A. Vigneron-Tenorio

The second Feng-Rao number of every inductive numerical semigroup is explicitly computed. This number determines the asymptotical behaviour of the order bound for the second Hamming weight of one-point AG codes. In particular, this result…

Information Theory · Computer Science 2015-05-07 J. I. Farrán , P. A. García-Sánchez

We derive polynomial identities of arbitrary degree $n$ for syzygies degrees of numerical semigroups S_m=<d_1,...,d_m> and show that for n>=m they contain higher genera G_r=\sum_{s\in Z_>\setminus S_m}s^r of S_m. We find a number…

Commutative Algebra · Mathematics 2020-12-25 Leonid G. Fel

The notion of almost symmetric numerical semigroup was given by V. Barucci and R. Fr\"oberg. We characterize almost symmetric numerical semigroups by symmetry of pseudo-Frobenius numbers. We give a criterion for $H^*$ (the dual of $M$) to…

Group Theory · Mathematics 2011-11-29 Hirokatsu Nari

We consider graph classes $\mathcal G$ in which every graph has components in a class $\mathcal{C}$ of connected graphs. We provide a framework for the asymptotic study of $\lvert\mathcal{G}_{n,N}\rvert$, the number of graphs in…

Combinatorics · Mathematics 2018-01-17 Konstantinos Panagiotou , Leon Ramzews

This paper is a continuation of the paper "Numerical Semigroups: Ap\'ery Sets and Hilbert Series". We consider the general numerical AA-semigroup, i.e., semigroups consisting of all non-negative integer linear combinations of relatively…

Commutative Algebra · Mathematics 2017-01-17 Ignacio García-Marco , Jorge L. Ramírez Alfonsín , Oystein J. Rodseth