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Related papers: Basic Orders for Defect Two Blocks of $\Z_p\Sym_n$

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We use the theory of blocks of cyclic defect to prove that under a certain condition on the principal p-block of a finite group G the normalized unit group of the integral group ring of G contains an element of order pq if and only if so…

Rings and Algebras · Mathematics 2020-04-09 Andreas Bächle , Leo Margolis

Let $p$ be a prime. In this paper, we compute complexities of some simple modules of symmetric groups labelled by two-part partitions. Most of the simple modules considered here are contained in the $p$-blocks with non-abelian defect…

Representation Theory · Mathematics 2018-10-03 Yu Jiang

Combinatorial mechanical metamaterials are made of anisotropic, flexible blocks, such that multiple metamaterials may be constructed using a single block type, and the system's response depends on the frustration (or its absence) due to the…

Soft Condensed Matter · Physics 2025-07-02 Chaviva Sirote-Katz , Yotam M. Y. Feldman , Guy Cohen , Tamás Kálmán , Yair Shokef

We compare lower defect groups associated with $p$-regular classes and vertices of simple modules for a block of a finite group algebra. We show that lower defect groups are contained in vertices of simple modules after suitable reordering.…

Representation Theory · Mathematics 2022-03-02 Akihiko Hida , Masao Kiyota

This paper is an attempt to compute the decomposition numbers of the blocks of the symmetric group which have "small defect"; that is, blocks of weight smaller than the characteristic. We present various methods for computing such…

Representation Theory · Mathematics 2007-05-23 Gordon James , Andrew Mathas

Suppose that all nontrivial subsections of a $p$-block $B$ are conjugate (where $p$ is a prime). By using the classification of the finite simple groups, we prove that the defect groups of $B$ are either extraspecial of order $p^3$ with $p…

Representation Theory · Mathematics 2014-10-22 Lázló Héthelyi , Radha Kessar , Burkhard Külshammer , Benjamin Sambale

Let $p$ be an odd prime and let $\mathbf{B}$ be a $p$-block of a finite group, such that $\mathbf{B}$ has cyclic defect groups. We describe the self-dual indecomposable $\mathbf{B}$-modules and for each such module determine whether it is…

Representation Theory · Mathematics 2024-12-18 Caroline Lassueur , John Murray

We show that two blocks of generalized quaternion defect with three simple modules over a sufficiently large $2$-adic ring $\mathcal O$ are Morita-equivalent if and only if the corresponding blocks over the residue field of $\mathcal O$ are…

Representation Theory · Mathematics 2015-06-18 Florian Eisele

We determine the structure of 2-blocks with minimal nonabelian defect groups, by making use of the classification of finite simple groups.

Representation Theory · Mathematics 2011-09-20 Charles Eaton , Burkhard Külshammer , Benjamin Sambale

In this paper, we classify all $2$-blocks for which the defect groups are abelian and the inertial quotient has prime order. As a consequence, we prove that Brou\'e's abelian defect group conjecture holds for all blocks under consideration…

Group Theory · Mathematics 2026-04-14 Qianhu Zhou , Kun Zhang

In this paper, following the methods of http://arxiv.org/abs/1305.7449v2, we show that the double covering groups of the symmetric and alternating groups have p-basic sets for any odd prime p.

Representation Theory · Mathematics 2016-06-09 Olivier Brunat , Jean-Baptiste Gramain

Let G be a finite group, and let B be a non-nilpotent block of G with respect to an algebraically closed field of characteristic 2. Suppose that B has an elementary abelian defect group of order 16 and only one simple module. The main…

Representation Theory · Mathematics 2016-05-20 Pierre Landrock , Benjamin Sambale

We give a new method to construct isolated left orderings of groups whose positive cones are finitely generated. Our construction uses an amalgamated free product of two groups having an isolated ordering. We construct a lot of new examples…

Group Theory · Mathematics 2013-02-21 Tetsuya Ito

A perfect isometry is an important relation between blocks of finite groups as many information about blocks are preserved by it. If we consider the group of all perfect isometries between a block to itself then this gives another…

Representation Theory · Mathematics 2016-10-27 Pornrat Ruengrot

We show that if the Sylow $p$-subgroup of a finite group $G$ is of order $p$, then the normalized unit group of the integral group ring of $G$ contains a normalized unit of order $pq$ if and only if $G$ contains an element of order $pq$,…

Group Theory · Mathematics 2021-01-06 Mauricio Caicedo , Leo Margolis

We obtain restrictions on units of even order in the integral group ring $\mathbb{Z}G$ of a finite group $G$ by studying their actions on the reductions modulo $4$ of lattices over the $2$-adic group ring $\mathbb{Z}_2G$. This improves the…

Rings and Algebras · Mathematics 2024-12-13 Florian Eisele , Leo Margolis

We show that the $p$-part of the degree of an irreducible character of a symmetric group is completely determined by the set of vanishing elements of $p$-power order. As a corollary we deduce that the set of zeros of prime power order…

Representation Theory · Mathematics 2025-11-18 Eugenio Giannelli , Stacey Law , Eoghan McDowell

For any block of a finite group over an algebraically closed field of characteristic $2$ which has dihedral, semidihedral, or generalized quaternion defect groups, we determine explicitly the decomposition of the associated diagonal…

Representation Theory · Mathematics 2025-09-19 Robert Boltje , Serge Bouc , Deniz Yılmaz

We prove that if $B$ is a $p$-block with non-trivial defect group $D$ of a finite $p$-solvable group $G$, then $\ell(B) < p^r$, where $r$ is the sectional rank of $D$. We remark that there are infinitely many $p$-blocks $B$ with non-Abelian…

Representation Theory · Mathematics 2016-11-08 Gunter Malle , Geoffrey R. Robinson

Let $k$ be a field of odd prime characteristic $p$. We calculate the Lie algebra structure of the first Hochschild cohomology of a class of quantum complete intersections over $k$. As a consequence, we prove that if $B$ is a defect…

Representation Theory · Mathematics 2016-04-18 David John Benson , Radha Kessar , Markus Linckelmann
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