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We report some group divisible designs with block size five, including types $6^{15}$ and $10^{15}$. As a consequence we are able to extend the known spectrum for 5-GDDs of type $g^u$.

Combinatorics · Mathematics 2022-07-06 Anthony D. Forbes

Computational techniques for the construction of quasi-symmetric block designs are explored and applied to the case with $56$ points. One new $(56,16,18)$ and many new $(56,16,6)$ designs are discovered, and non-existence of $(56,12,9)$ and…

Combinatorics · Mathematics 2025-09-30 Vedran Krčadinac , Renata Vlahović Kruc

This work focuses on non-adaptive combinatorial group testing, with a primary goal of efficiently identifying a set of at most $d$ defective elements among a given set of $n$ elements using the fewest possible tests. Non-adaptive…

Information Theory · Computer Science 2026-04-28 Daniil Goshkoder , Nikita Polyanskii , Ilya Vorobyev

To each pair consisting of a saturated fusion system over a $p$-group together with a compatible family of K\"ulshammer-Puig cohomology classes, one can count weights in a hypothetical block algebra arising from these data. When the pair…

Group Theory · Mathematics 2019-06-25 Justin Lynd , Jason Semeraro

We consider the existence problem for a semi-cyclic holey group divisible design of type (n,m^t) with block size 3, which is denoted by a 3-SCHGDD of type (n,m^t). When t is odd and n\neq 8 or t is doubly even and t\neq 8, the existence…

Combinatorics · Mathematics 2014-10-23 Tao Feng , Xiaomiao Wang , Ruizhong Wei

Using the classification of finite simple groups we prove Alperin's weight conjecture and the character theoretic version of Broue's abelian defect group conjecture for 2-blocks of finite groups with an elementary abelian defect group of…

Representation Theory · Mathematics 2010-12-17 Radha Kessar , Shigeo Koshitani , Markus Linckelmann

The band-unfolding method is widely used to calculate the effective band structures of a disordered system from its supercell model. The unfolded band structures show the crystallographic symmetry of the underlying structure, where the…

Materials Science · Physics 2017-01-18 Yuji Ikeda , Abel Carreras , Atsuto Seko , Atsushi Togo , Isao Tanaka

In this paper we will consider the 2-fold symmetric complex hyperbolic triangle groups generated by three complex reflections through angle 2pi/p with p no smaller than 2. We will mainly concentrate on the groups where some elements are…

Algebraic Topology · Mathematics 2017-04-20 John R. Parker , Li-Jie Sun

We prove a conjecture by Belmans, Fu and Krug concerning the Hochschild homology of the symmetric powers of a small dg category $\mathscr{C}$. More precisely, we show that these groups decompose into pieces that only depend on the…

Category Theory · Mathematics 2026-01-21 Ville Nordstrom

The paper investigates exterior and symmetric (co)homologies of groups. We introduce symmetric homology of groups and compute exterior and symmetric (co)homologies of some finite groups. We also compare the classical, exterior and symmetric…

Group Theory · Mathematics 2021-07-19 Valeriy G. Bardakov , Mikhail V. Neshchadim , Mahender Singh

The tensor rank decomposition is a useful tool for the geometric interpretation of the tensors in the canonical tensor model (CTM) of quantum gravity. In order to understand the stability of this interpretation, it is important to be able…

General Relativity and Quantum Cosmology · Physics 2021-07-22 Dennis Obster , Naoki Sasakura

We study a weakened version of the Holm--Willems Local Conjecture. The problem is reduced to quasi-simple groups under the assumption that the defect group is abelian. Complete proofs are provided in the case \(p = 2\).

Group Theory · Mathematics 2026-04-14 Hanxiao Li , Kun Zhang

For any prime p, we construct, and simultaneously count, all of the complex Specht modules in a given p-block of the symmetric group which remain irreducible when reduced modulo p. We call the Specht modules with this property p-irreducible…

Combinatorics · Mathematics 2007-05-23 James P. Cossey , Matthew Ondrus , C. Ryan Vinroot

This paper investigates the critical group of a faithful representation of a finite group. It computes the order of the critical group in terms of the character values, and gives some restrictions on its subgroup structure. It also computes…

Combinatorics · Mathematics 2016-10-14 Christian Gaetz

We introduce group crosscoders, an extension of crosscoders that systematically discover and analyse symmetrical features in neural networks. While neural networks often develop equivariant representations without explicit architectural…

Machine Learning · Computer Science 2024-11-04 Liv Gorton

A Space-Time Block Code (STBC) in $K$ symbols (variables) is called $g$-group decodable STBC if its maximum-likelihood decoding metric can be written as a sum of $g$ terms such that each term is a function of a subset of the $K$ variables…

Information Theory · Computer Science 2007-07-16 Sanjay Karmakar , B. Sundar Rajan

In this paper we study how certain symmetries of convex bodies affect their geometric properties. In particular, we consider the impact of symmetries generated by the block diagonal subgroup of orthogonal transformations, generalizing…

Functional Analysis · Mathematics 2015-01-14 Susanna Dann , Marisa Zymonopoulou

We start by introducing the basics of configurations of points and lines, and then move into discussing symmetry groups of these configurations. Specifically, we explore how we might classify the symmetries of $(9_3)$ and $(10_3)$ geometric…

Combinatorics · Mathematics 2021-09-01 Luke Boyer , Nick Payne

We introduce polyhedral cones associated with $m$-hemimetrics on $n$ points, and, in particular, with $m$-hemimetrics coming from partitions of an $n$-set into $m+1$ blocks. We compute generators and facets of the cones for small values of…

Combinatorics · Mathematics 2007-05-23 M. Deza , I. Rosenberg

We develop an elementary algebraic method to compute the center of the principal block of a small quantum group associated with a complex semisimple Lie algebra at a root of unity. The exemplary case of $\mathfrak{sl}_3$ is computed…

Representation Theory · Mathematics 2021-03-04 Anna Lachowska , You Qi