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For any finite type connected surface $S$, we give an infinite presentation of the fundamental group $\pi_1(S,\ast)$ of $S$ based at an interior point $\ast\in{S}$ whose generators are represented by simple loops. When $S$ is…

Geometric Topology · Mathematics 2023-03-08 Ryoma Kobayashi

Let $F$ be a finite extension of $\mathbb{Q}_p$. We prove that the category of finitely presented smooth $Z$-finite representations of $GL_2(F)$ over a finite extension of $\mathbb{F}_p$ is an abelian subcategory of the category of all…

Representation Theory · Mathematics 2020-07-28 Jack Shotton

We present a uniform methodology for computing with finitely generated matrix groups over any infinite field. As one application, we completely solve the problem of deciding finiteness in this class of groups. We also present an algorithm…

Group Theory · Mathematics 2019-05-14 A. S. Detinko , D. L. Flannery , E. A. O'Brien

By a [$K$-]approximate subring of a ring we mean an additively symmetric subset $X$ such that $X \cdot X \cup (X + X)$ is covered by finitely many [resp.\ $K$] additive translates of $X$. We prove a structure theorem for finite approximate…

Rings and Algebras · Mathematics 2026-04-07 Krzysztof Krupiński , Simon Machado

In 2007, Jarden and Narkiewicz raised the following question: Is it true that each algebraic number field has a finite extension L such that the ring of integers of L is generated by its units (as a ring)? In this article, we answer the…

Number Theory · Mathematics 2013-11-20 Christopher Frei

In this note we prove that if $G$ is a finitely generated profinite group then the verbal subgroup $G^{q}$ is open. Equivalently in a $d$-generator finite group every product of $q$th powers is a product of $f(d,q)$ $q$th powers.

Group Theory · Mathematics 2009-09-28 Dan Segal , Nikolay Nikolov

We prove that second rational homology of the Torelli group of an orientable closed surface of genus g is finite dimensional for g at least 51. This rules out the simplest obstruction to the Torelli group being finitely presented and…

Geometric Topology · Mathematics 2025-04-08 Daniel Minahan

We prove that the log canonical ring of a projective log canonical pair in Kodaira dimension two is finitely generated.

Algebraic Geometry · Mathematics 2023-02-14 Haidong Liu

We consider the class of all commutative reduced rings for which there exists a finite subset T of A such that all projections on quotients by prime ideals of A are surjective when restricted to T. A complete structure theorem is given for…

Commutative Algebra · Mathematics 2009-03-17 Antonio Avilés

We count the number of irreducible polynomials in several variables of a given degree over a finite field. The results are expressed in terms of a generating series, an exact formula and an asymptotic approximation. We also consider the…

Algebraic Geometry · Mathematics 2009-10-16 Arnaud Bodin

We show that every finitely generated residually finite torsion group $G$ embeds in a finitely generated torsion group $\Gamma$ that is residually finite simple. In particular we show the existence of finitely generated infinite torsion…

Group Theory · Mathematics 2024-07-09 Eduard Schesler

In SGA 2, Grothendieck conjectures that the \'etale fundamental group of the punctured spectrum of a complete noetherian local domain of dimension at least two with algebraically closed residue field is topologically finitely generated. In…

Number Theory · Mathematics 2023-07-21 Takashi Suzuki

To the best of our knowledge, there is no explicit, constructive description of the generating set for the unit group $A(G)^\times$ of the Burnside ring associated with a finite group $G$. We resolve this long-standing open question,…

Rings and Algebras · Mathematics 2025-09-09 Ziad Ghanem

Let $\mathcal{R}$ be a finite valuation ring of order $q^r$. In this paper we generalize and improve several well-known results, which were studied over finite fields $\mathbb{F}_q$ and finite cyclic rings $\mathbb{Z}/p^r\mathbb{Z}$, in the…

Combinatorics · Mathematics 2016-11-22 Pham Van Thang , Le Anh Vinh

In this paper, we discuss a proof of existence of log minimal models or Mori fibre spaces for klt pairs $(X/Z,B)$ with $B$ big$/Z$. This then implies existence of klt log flips, finite generation of klt log canonical rings, and most of the…

Algebraic Geometry · Mathematics 2009-04-21 Caucher Birkar , Mihai Paun

Let G be a linear algebraic group defined over a finite field F_q. We present several connections between the isogenies of G and the finite groups of rational points G(F_q^n). We show that an isogeny from G' to G over F_q gives rise to a…

Group Theory · Mathematics 2022-07-19 Davide Sclosa

We show that every finitely generated cohomologically trivial module over $RG$, where $G$ is a finite $p$-group and $R$ is a $p$-adic ring, splits as the direct sum of a finite cohomologically trivial $RG$-module and a free $RG$-module.…

Group Theory · Mathematics 2025-10-24 Yassine Guerboussa , Maria Guedri

We give a simplified complete proof for the classification of the selfinjective representation-finite algebras of finite dimension over an algebraically closed field. We explain the relations between the two different approaches and also to…

Representation Theory · Mathematics 2023-05-30 Klaus Bongartz

Let $p: S\to S_g$ be a finite covering of an orientable closed surface of genus $g$. We prove that, for $g\geq 3$, the rational homology group $H_1(S;{\mathbb Q})$ is generated by cycles supported on simple closed curves $\gamma\subset S$…

Geometric Topology · Mathematics 2023-05-24 Marco Boggi

We determine the structure of the intersection of a finitely generated subgroup of a semiabelian variety $G$ defined over a finite field with a closed subvariety $X\subset G$.

Number Theory · Mathematics 2007-05-23 Dragos Ghioca