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Closed essential surfaces in a three-manifold can be detected by ideal points of the character variety or by algebraic non-integral representations. We give examples of closed essential surfaces not detected in either of these ways. For…

Geometric Topology · Mathematics 2018-08-15 Alex Casella , Charles Katerba , Stephan Tillmann

We show that the bounded Borel class of any dense representation $\rho: G\to \PSL_n\bC$ is non-zero in degree three bounded cohomology and has maximal semi-norm, for any discrete group $G$. When $n=2$, the Borel class is equal to the…

Geometric Topology · Mathematics 2021-03-11 James Farre

We show that the Nichols algebra of a simple Yetter-Drinfeld module over a projective special linear group over a finite field whose support is a semisimple orbit has infinite dimension, provided that the elements of the orbit are…

Quantum Algebra · Mathematics 2024-11-01 N. Andruskiewitsch , G. Carnovale , G. García

This work provides five explicit constructions of the exceptional Lie algebra $\mathfrak{e}_8$, based on its semisimple subalgebras of maximal rank. Each of these models is graded by an abelian group, namely, $\mathbb{Z}_4$, $\mathbb{Z}_5$,…

Rings and Algebras · Mathematics 2025-08-12 Yolanda Cabrera , Cristina Draper , Antonio Garvin

Exceptional sequences are important sequences of quiver representations in the study of representation theory of algebras. They are also closely related to the theory of cluster algebras and the combinatorics of Coxeter groups. We…

Representation Theory · Mathematics 2020-04-20 Emily Carrick , Alexander Garver

Let M be a graph manifold. We prove that fundamental groups of embedded incompressible surfaces in M are separable in the fundamental group of M, and that the double cosets for crossing surfaces are also separable. We deduce that if there…

Geometric Topology · Mathematics 2014-01-17 Piotr Przytycki , Daniel T. Wise

We construct explicit local systems on the affine line in characteristic $p>2$, whose geometric monodromy groups are the finite symplectic groups $Sp_{2n}(q)$ for all $n \ge 2$, and others whose geometric monodromy groups are the special…

Number Theory · Mathematics 2020-11-04 Nicholas M. Katz , Pham Huu Tiep

We analyze irreducible plane sextics whose fundamental group factors to $D_{14}$. We produce explicit equations for all curves and show that, in the simplest case of the set of singularities $3A_6$, the group is $D_{14}\times Z_3$.

Algebraic Geometry · Mathematics 2010-05-07 Alex Degtyarev , Mutsuo Oka

We explore the relationship between (3-isogeny induced) Selmer group of an elliptic curve and the (3 part of) the ideal class group, over certain non-abelian number fields.

Number Theory · Mathematics 2025-06-11 Abhishek , Debanjana Kundu

Let $X$ be a toric Del-Pezzo surface and let $Crit(W) \subset (\mathbb{C}^{\ast})^n$ be the solution scheme of the Landau-Ginzburg system of equations. Denote by $X^{\circ}$ the polar variety of $X$. Our aim in this work is to describe a…

Algebraic Geometry · Mathematics 2017-05-22 Yochay Jerby

Let $p$ be an odd prime and $S$ a nonabelian finite $p$-group. In [9, 10], they proposed the following conjecture: if $\mathcal{F}$ be a transitive fusion system over a finite $p$-group $S$, then $S$ is either extraspecial of order $p^{3}$…

Group Theory · Mathematics 2024-12-05 Rui Gao , Heguo Liu , Xingzhong Xu , Sheng Yang

Let G be a finite group, Irr(G) the set of all irreducible complex characters of G and X \in Irr(G). Let also cod(X) = |G : kerX|/X(1) and cod(G) = {cod(X) | X \in Irr(G)}. In this note, we show that the simple group PSL(2, q), for a prime…

Group Theory · Mathematics 2026-02-18 Afsane Bahri , Zeinab Akhlaghi , Behrooz Khosravi

In this paper, we give a classification of the subgroups of $\textrm{PSL}(3, \mathbb{C})$ that act on $\mathbb{P}_{\mathbb{C}}^2$ in such a way that their Kulkarni limit set has finitely many lines in general position lines. These are the…

Group Theory · Mathematics 2023-07-11 Waldemar Barrera , Angel Cano , Juan Pablo Navarrete , José Seade

We introduce the notion of graphical discreteness to group theory. A finitely generated group is graphically discrete if whenever it acts geometrically on a locally finite graph, the automorphism group of the graph is compact-by-discrete.…

Group Theory · Mathematics 2025-11-20 Alex Margolis , Sam Shepherd , Emily Stark , Daniel Woodhouse

We show that Nichols algebras of most simple Yetter-Drinfeld modules over the projective special linear group over a finite field, corresponding to semisimple orbits, have infinite dimension. We introduce a new criterium to determine when a…

Quantum Algebra · Mathematics 2018-03-14 Nicolás Andruskiewitsch , Giovanna Carnovale , Gastón Andrés García

We prove that convex-cocompact representations of finitely generated groups in the group of isometries of the infinite-dimensional hyperbolic space form an open set in the space of representations, allowing us to deform these…

Geometric Topology · Mathematics 2026-03-10 David Xu

A group is said to be cube-free if its order is not divisible by the cube of any prime. Let $f_{cf,sol}(n)$ denote the isomorphism classes of solvable cube-free groups of order $n$. We find asymptotic bounds for $f_{cf,sol}(n)$ in this…

Group Theory · Mathematics 2025-07-08 Prashun Kumar , Geetha Venkataraman

Let G be a connected simple adjoint p-adic group not isomorphic to a projective linear group PGL(m,D) of a division algebra D, or an adjoint ramified unitary group of a split hermitian form in 3 variables. We prove that G admits an…

Number Theory · Mathematics 2018-01-01 Marie-France Vignéras

The symmetry algebra of the real elliptic Liouville equation is an infinite-dimensional loop algebra with the simple Lie algebra $o(3,1)$ as its maximal finite-dimensional subalgebra. The entire algebra generates the conformal group of the…

Exactly Solvable and Integrable Systems · Physics 2018-11-14 Decio Levi , Luigi Martina , Pavel Winternitz

We prove that all finitely generated fully residually free groups (limit groups) have a sequence of finite dimensional unitary representations that `strongly converge' to the regular representation of the group. The corresponding statement…

Group Theory · Mathematics 2023-01-18 Larsen Louder , Michael Magee with Appendix by Will Hide , Michael Magee