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This note is an attempt to generalize Bolibruch's theorem from the projective line to curves of higher genus. We show that an irreducible representation of the fundamental group of an open in a curve of higher genus has always a…

Algebraic Geometry · Mathematics 2007-05-23 Hélène Esnault , Eckart Viehweg

Suppose that $\mathcal{C}$ is a class of groups consisting only of periodic groups and $\mathfrak{P}(\mathcal{C})^{\prime}$ is the set of prime numbers each of which does not divide the order of any element of a $\mathcal{C}$-group. A…

Group Theory · Mathematics 2022-02-07 E. V. Sokolov

It was earlier conjectured by the second and the third authors that any rational curve $g:{\mathbb C}P^1\to {\mathbb C}P^n$ such that the inverse images of all its flattening points lie on the real line ${\mathbb R}P^1\subset {\mathbb…

Algebraic Geometry · Mathematics 2007-05-23 T. Ekedahl , B. Shapiro , M. Shapiro

Attached to a singular analytic curve germ in $d$-space is a numerical semigroup: a subset $S$ of the non-negative integers which is closed under addition and whose complement isfinite. Conversely, associated to any numerical semigroup $S$…

Algebraic Geometry · Mathematics 2024-03-06 Richard Montgomery

We give a self-contained introduction to linear algebraic and semialgebraic groups over real closed fields, and we generalize several key results about semisimple Lie groups to algebraic and semialgebraic groups over real closed fields. We…

Group Theory · Mathematics 2026-01-13 Raphael Appenzeller

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

For any ring $R$, we introduce an invariant in the form of a partially ordered abelian semigroup $\mathrm{S}(R)$ built from an equivalence relation on the class of countably generated projective modules. We call $\mathrm{S}(R)$ the Cuntz…

Rings and Algebras · Mathematics 2023-07-17 Ramon Antoine , Pere Ara , Joan Bosa , Francesc Perera , Eduard Vilalta

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…

In this paper we give an algorithm for the computation of all the Arf numerical semigroups with a given genus. Moreover, we generalize the concept of genus of a numerical semigroup to good semigroups of $\mathbb{N}^r$ and we give a…

Commutative Algebra · Mathematics 2018-02-09 Giuseppe Zito

We investigate the structure of the generalized Weierstrass semigroups at several points on a curve defined over a finite field. We present a description of these semigroups that enables us to deduce properties concerned with the…

Algebraic Geometry · Mathematics 2025-01-17 Julio José Moyano-Fernández , Wanderson Tenório , Fernando Torres

In this article, we first prove that the type of an affine semigroup ring is equal to the number of maximal elements of the Ap\'ery set with respect to the set of exponents of the monomials, which form a maximal regular sequence. Further,…

Commutative Algebra · Mathematics 2026-03-02 Om Prakash Bhardwaj , Carmelo Cisto

In this paper, we study good semigroups of \mathbb{N}^n, a class of semigroups that contains the value semigroups of algebroid curves with n branches. We give the definition of embedding dimension of a good semigroup showing that, in the…

Commutative Algebra · Mathematics 2019-05-03 Nicola Maugeri , Giuseppe Zito

Let C be a complete non-singular irreducible curve of genus 4 over an algebraically closed field of characteristic 0. We determine all possible Weierstrass semigroups of ramification points on double covers of C which have genus greater…

Algebraic Geometry · Mathematics 2013-10-08 S. J. Kim , J. Komeda

Semigroup theory is a branch of abstract algebra, and it provides mathematical tools for the theory of computation. Finite semigroups can describe state transition systems and thus they model physically realizable computers. Engineering…

Group Theory · Mathematics 2026-01-22 James East , Attila Egri-Nagy , Andrew R. Francis , James D. Mitchell

Let $G$ be a finite group and, for a given complex character $\chi$ of $G$, let ${\mathbb{Q}}(\chi)$ denote the field extension of ${\mathbb{Q}}$ obtained by adjoining all the values $\chi(g)$, for $g\in G$. The group $G$ is called…

Group Theory · Mathematics 2025-04-10 Emanuele Pacifici , Marco Vergani

In this paper we provide some factorization theorems of the Poincar\'e series $P_C$ of a plane curve singularity $C$ depending on some key values of the semigroup of values of \(C\). These results yield an iterative computation of $P_C$ in…

Algebraic Geometry · Mathematics 2023-05-12 Patricio Almirón , Julio-José Moyano-Fernández

In this paper, we study configurations of three rational points on the Hermitian curve over $\mathbb{F}_{q^2}$ and classify them according to their Weierstrass semigroups. For $q>3$, we show that the number of distinct semigroups of this…

Algebraic Geometry · Mathematics 2020-11-17 Gretchen L. Matthews , Dane Skabelund , Michael Wills

All rational parametric curves with prescribed polynomial tangent direction form a vector space. Via tangent directions with rational norm, this includes the important case of rational Pythagorean hodograph curves. We study vector subspaces…

Metric Geometry · Mathematics 2023-01-31 Hans-Peter Schröcker , Zbyněk Šír

Let $C\subset\mathbb{N}^p$ be an integer polyhedral cone. An affine semigroup $S\subset C$ is a $ C$-semigroup if $| C\setminus S|<+\infty$. This structure has always been studied using a monomial order. The main issue is that the choice of…

Commutative Algebra · Mathematics 2024-09-05 D. Marín-Aragón , R. Tapia-Ramos

For any complex number $c$, let $\sigma_c\colon\mathbb N\rightarrow\mathbb C$ denote the divisor function defined by $\sigma_c(n)=\displaystyle{\sum_{d|n}d^c}$ for all $n\in\mathbb N$, and define $R(c)=\{\sigma_c(n)\in\mathbb C\colon…

Number Theory · Mathematics 2018-01-11 Colin Defant