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In this article, we prove that every finite abelian group $G$ of odd order occurs as a subgroup of the class group of infinitely many real cyclotomic fields.

Number Theory · Mathematics 2021-03-15 Mohit Mishra

We generalise the Elekes-Szab\'o theorem to arbitrary arity and dimension and characterise the complex algebraic varieties without power saving. The characterisation involves certain algebraic subgroups of commutative algebraic groups…

Combinatorics · Mathematics 2022-09-13 Martin Bays , Emmanuel Breuillard

Davis and Jedwab (1997) established a great construction theory unifying many previously known constructions of difference sets, relative difference sets and divisible difference sets. They introduced the concept of building blocks, which…

Combinatorics · Mathematics 2020-06-01 Koji Momihara

We prove new general results on sumsets of sets having Szemer\'edi--Trotter type. This family includes convex sets, sets with small multiplicative doubling, images of sets under convex/concave maps and others.

Combinatorics · Mathematics 2014-10-22 Ilya D. Shkredov

In this work, we introduce a new class of algebras called skew-Brauer graph algebras, which generalize the well-known Brauer graph algebras. We establish that skew-Brauer graph algebras are symmetric and can be defined using a Brauer graph…

Representation Theory · Mathematics 2025-11-24 Ana García Elsener , Victoria Guazzelli , Yadira Valdivieso

We show that the invariants of a free associative algebra of finite rank under a linear action of a finite-dimensional Hopf algebra generated by group-like and skew-primitive elements form a finitely generated algebra exactly when the…

Rings and Algebras · Mathematics 2007-05-23 Vitor O. Ferreira , Lucia S. I. Murakami

We make several new contributions to the study of proper holomorphic mappings between balls. Our results include a degree estimate for rational proper maps, a new gap phenomenon for convex families of arbitrary proper maps, and an…

Complex Variables · Mathematics 2009-06-01 John P D'Angelo , Jiri Lebl

The present work is devoted to characterize the family of symmetric undirected Cayley graphs over finite Abelian groups for degrees 4 and 6.

Combinatorics · Mathematics 2014-03-31 Cristóbal Camarero , Carmen Martínez , Ramón Beivide

This work investigates the existence of complex structures on 2-step nilpotent Lie algebras arising from finite graphs. We introduce the notion of adapted complex structure, namely a complex structure that maps vertices and edges of the…

Differential Geometry · Mathematics 2025-12-30 Adrián Andrada , Sonia Vera

We obtain deformations of a crossed product of a polynomial algebra with a group, under some conditions, from universal deformation formulas. We show that the resulting deformations are nontrivial by a comparison with Hochschild cohomology.…

Rings and Algebras · Mathematics 2007-05-23 Sarah J. Witherspoon

We extend the existing skew polynomial representations of matrix algebras which are direct sum of matrix spaces over division rings. In this representation, the sum-rank distance between two tuples of matrices is captured by a weight…

Information Theory · Computer Science 2025-12-10 Alessandro Neri , Paolo Santonastaso

An imprimitive symmetric indecomposable association scheme of rank 5 is said to be Higmanian. A divisible design graph is a graph whose adjacency matrix is an incidence matrix of a symmetric divisible design. We establish conditions which…

Combinatorics · Mathematics 2026-01-27 Grigory Ryabov

We define skew Schubert polynomials to be normal form (polynomial) representatives of certain classes in the cohomology of a flag manifold. We show that this definition extends a recent construction of Schubert polynomials due to Bergeron…

Combinatorics · Mathematics 2010-03-29 Cristian Lenart , Frank Sottile

We present a novel construction of finite groupoids whose Cayley graphs have large girth even w.r.t. a discounted distance measure that contracts arbitrarily long sequences of edges from the same colour class (sub-groupoid), and only counts…

Combinatorics · Mathematics 2024-01-17 Martin Otto

Totally symmetric sets are a recently introduced tool for studying homomorphisms between groups. In this paper, we give full classifications of totally symmetric sets in certain families of groups and bound their sizes in others. As a…

Group Theory · Mathematics 2022-03-09 Kevin Kordek , Qiao Li , Caleb Partin

Skew morphisms, which generalise automorphisms for groups, provide a fundamental tool for the study of regular Cayley maps and, more generally, for finite groups with a complementary factorisation $G=BY$, where $Y$ is cyclic and core-free…

Combinatorics · Mathematics 2019-05-03 Martin Bachratý , Marston Conder , Gabriel Verret

Using the affine web category introduced in a prequel as a building block, we formulate a diagrammatic $\Bbbk$-linear monoidal category, the affine Schur category, for any commutative ring $\Bbbk$. We then formulate diagrammatic categories,…

Representation Theory · Mathematics 2024-12-25 Linliang Song , Weiqiang Wang

With an explicit, algebraic indexing $(2,1)$-category, we develop an efficient homotopy theory of cyclonic objects: circle-equivariant objects relative to the family of finite subgroups. We construct an $\infty$-category of cyclotomic…

Algebraic Topology · Mathematics 2016-02-09 Clark Barwick , Saul Glasman

We explicitly describe the derived Picard groups of symmetric representation-finite algebras of type $D$. In particular, we prove that these groups are generated by spherical twists along collections of $0$-spherical objects, the shift and…

Representation Theory · Mathematics 2026-02-17 Anya Nordskova

We give two new constructions of almost difference sets. The first is a generic construction of $(q^{2}(q+1),q(q^{2}-1),q(q^{2}-q-1),q^{2}-1)$ almost difference sets in certain groups of order $q^{2}(q+1)$ ($q$ is an odd prime power) having…

Combinatorics · Mathematics 2018-07-27 Jerod Michel , Qi Wang