Mullineux map: $d$-balanced partitions and $d$-runner matrices

Fuente: arXiv
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Autore principale: Turek, Pavel
Natura: Preprint
Pubblicazione: 2025
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author Turek, Pavel
author_facet Turek, Pavel
contents Let $1<d<e$ be two coprime integers and let $m_e$ denote the Mullineux map, which for $e$ prime describes tensor products of the irreducible modules of symmetric groups with the sign in characteristic $e$. We prove that if $λ$ is an $e$-regular partition such that $d$ divides the arm length of any rim hook of $λ$ of size divisible by $e$, then $m_e(λ)'$ is a partition such that the arm length of any of its rim hooks of size divisible by $e$ is congruent to $-1$ modulo $d$. We introduce a new parameter for partitions called the $d$-runner matrix and show that if $λ$ is as above, then the $d$-runner matrices of $λ$ and $m_e(λ)'$ agree. This determines $m_e(λ)'$ uniquely. We approach the whole problem combinatorially and take advantage of a new Abacus Mullineux Algorithm introduced in this paper. We also establish equivalent descriptions of the above partitions which provide an alternative version of the main result about the Mullineux map, which becomes particularly strong when $d=2$.
format Preprint
id arxiv_https___arxiv_org_abs_2504_03864
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Mullineux map: $d$-balanced partitions and $d$-runner matrices
Turek, Pavel
Combinatorics
Representation Theory
05E10 (Primary), 20C30 (Secondary)
Let $1<d<e$ be two coprime integers and let $m_e$ denote the Mullineux map, which for $e$ prime describes tensor products of the irreducible modules of symmetric groups with the sign in characteristic $e$. We prove that if $λ$ is an $e$-regular partition such that $d$ divides the arm length of any rim hook of $λ$ of size divisible by $e$, then $m_e(λ)'$ is a partition such that the arm length of any of its rim hooks of size divisible by $e$ is congruent to $-1$ modulo $d$. We introduce a new parameter for partitions called the $d$-runner matrix and show that if $λ$ is as above, then the $d$-runner matrices of $λ$ and $m_e(λ)'$ agree. This determines $m_e(λ)'$ uniquely. We approach the whole problem combinatorially and take advantage of a new Abacus Mullineux Algorithm introduced in this paper. We also establish equivalent descriptions of the above partitions which provide an alternative version of the main result about the Mullineux map, which becomes particularly strong when $d=2$.
title Mullineux map: $d$-balanced partitions and $d$-runner matrices
topic Combinatorics
Representation Theory
05E10 (Primary), 20C30 (Secondary)
url https://arxiv.org/abs/2504.03864