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We prove that some aspherical manifolds do not have BIP, negating a question of Jiang.

Geometric Topology · Mathematics 2024-11-12 Qiang Zhang , Xuezhi Zhao

We show that infinitely many alternating groups arise as quotients of the free group of rank 2, with kernel a characteristic subgroup. We also show that such simple quotients exist of arbitrarily large Lie rank. This resolves two questions…

Group Theory · Mathematics 2025-10-06 Liam Hanany

In this note we prove that if $\mathbb{M}(U,\tau)$ is a special Moufang set and $a\in U^*$, then C_U(a) is abelian.

Group Theory · Mathematics 2010-11-09 Yoav Segev

Let G be the fundamental group of the complement of a K(G,1) hyperplane arrangement (such as Artin's pure braid group) or more generally a homologically toroidal group (as defined in the paper). The subgroup of elements in the complex…

Algebraic Topology · Mathematics 2007-05-23 Alejandro Adem , Daniel C. Cohen , Frederick R. Cohen

The number of nonisomorphic simplicial complexes with up to $n$ vertices increases super-exponentially with $n$, which makes exhaustive computation of invariants associated with such complexes a daunting task. In this paper we provide a…

Algebraic Topology · Mathematics 2025-11-05 Dejan Govc , Wacław Marzantowicz , Łukasz Patryk Michalak , Petar Pavešić

Suppose that M is an infinite structure with finite relational vocabulary such that every relation symbol has arity at most 2. If M is simple and homogeneous then its complete theory is supersimple with finite SU-rank which cannot exceed…

Logic · Mathematics 2015-04-08 Vera Koponen

We study closed subgroups $G$ of the automorphism group of a locally finite tree $T$ acting doubly transitively on the boundary. We show that if the stabiliser of some end is metabelian, then there is a local field $k$ such that…

Group Theory · Mathematics 2019-12-19 Pierre-Emmanuel Caprace , Tom De Medts

All nonabelian finite simple groups of rank $n$ over a field of size $q$, with the possible exception of the Ree groups $^2G_2(3^{2e+1})$, have presentations with at most $80 $ relations and bit-length $O(\log n +\log q)$. Moreover, $A_n$…

Group Theory · Mathematics 2008-04-10 R. M. Guralnick , W. M. Kantor , M. Kassabov , A. Lubotzky

The symplectic group branching algebra, B, is a graded algebra whose components encode the multiplicities of irreducible representations of Sp(2n-2,C) in each irreducible representation of Sp(2n,C). By describing on B an ASL structure, we…

Representation Theory · Mathematics 2012-09-03 Sangjib Kim , Oded Yacobi

We prove that a Murai sphere is flag if and only if it is a nerve complex of a flag nestohedron and classify all the polytopes arising in this way. Our classification implies that flag Murai spheres satisfy the Nevo-Petersen conjecture on…

Combinatorics · Mathematics 2024-11-22 Ivan Limonchenko , Rade Živaljević

The only known examples of noncompact Einstein homogeneous spaces are standard solvmanifolds (special solvable Lie groups endowed with a left invariant metric), and according to a long standing conjecture, they might be all. The…

Differential Geometry · Mathematics 2008-02-20 Cynthia E. Will

Let G be a simple algebraic group over an algebraically closed field k. We classify the spherical conjugacy classes of G.

Group Theory · Mathematics 2016-10-05 Mauro Costantini

We introduce the non-pure versions of simplicial balls and spheres with minimum number of vertices. These are a special type of non-homogeneous balls and spheres (NH-balls and NH-spheres) satisfying a minimality condition on the number of…

Combinatorics · Mathematics 2014-06-26 Nicolas Ariel Capitelli

We provide two examples which show that for an affine semigroup ring the set of Cohen-Macaulay classes can be larger than the set of conic classes.

Commutative Algebra · Mathematics 2007-05-23 Cornel Baetica

We provide a new branching rule from the general linear group $GL_{2n}(\mathbb{C})$ to the symplectic group $Sp_{2n}(\mathbb{C})$ by establishing a simple algorithm which gives rise to a bijection from the set of semistandard tableaux of a…

Representation Theory · Mathematics 2025-05-14 Hideya Watanabe

We investigate the multiplication group of a special class of quasigroup called AG-group. We prove some interesting results such as: the multiplication group of an AG-group of order n is non-abelian group of order 2n and its left section is…

Group Theory · Mathematics 2016-06-21 Muhammad Shah , Asif Ali , Imtiaz Ahmad , Volker Sorge

We determine all spherical algebraic subalgebras in any simple Lie algebra of real rank 1.

Representation Theory · Mathematics 2018-05-08 Lisa Knauss , Christian Miebach

Groups definable in simple theories retain the chain conditions and decomposition properties known from stable groups, up to commensurability. In the small case, if a generic type of G is not foreign to some type q, there is a q-internal…

Group Theory · Mathematics 2008-02-03 Frank Wagner

We introduce a new invariant, the real (logarithmic)-Kodaira dimension, that allows to distinguish smooth real algebraic surfaces up to birational diffeomorphism. As an application, we construct infinite families of smooth rational real…

Algebraic Geometry · Mathematics 2023-06-22 Jérémy Blanc , Adrien Dubouloz

We show that there exist non-trivial families of algebraic varieties for which all the fibers above rational points (or even above points of odd degree) are torsors of abelian varieties representing nonzero elements of their…

Number Theory · Mathematics 2017-04-03 Jean-Louis Colliot-Thelene , Bjorn Poonen