Shigeo Koshitani

activity

20092026

most citedBroué's abelian defect group conjecture for the sporadic simple Janko group J_4 revisited

1 citations · 1 across the 3 of their papers we have counts for

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math.RT2026

The Mathieu group $M_{12}$ vs $S L_{3} (3)$ in characteristic 3

Shigeo Koshitani, Tetsuro Okuyama

We prove that the principal $3$ -blocks of the Mathieu group $M_{12}$ and the special linear group $\SL_3(3)$ are splendidly Rickard equivalent, and hence derived equivalent,…

math.RT2026

A reciprocity theorem of Robinson-Benson-Webb for finite-dimensional symmetric algebras

Shigeo Koshitani

We generalize the reciprocity theorem of G.R.~Robinson, D. Benson and P. Webb between a finite group and its subgroup to the case of finite-dimensional {\it symmetric} algebras ove…

math.RT2024

Lifting Brauer indecomposability of a Scott module

Shigeo Koshitani, İpek Tuvay

It is proven that if a finite group $G$ has a normal subgroup $H$ with $p^{'}$ -index (where $p$ is a prime) and $G / H$ is solvable, then for a $p$ -subgroup $P$ of $H$ , if the Scott $kH…

math.RT2023

Principal 2-blocks with wreathed defect groups up to splendid Morita equivalence

Shigeo Koshitani, Caroline Lassueur, Benjamin Sambale

We classify principal $2$ -blocks of finite groups $G$ with Sylow $2$ -subgroups isomorphic to a wreathed $2$ -group $C_{2^{n}} ≀ C_{2}$ with $n \geq 2$ up to Morita equivalence and up to…

math.RT2020

Splendid Morita equivalences for principal blocks with semidihedral defect groups

Shigeo Koshitani, Caroline Lassueur, Benjamin Sambale

We classify principal blocks of finite groups with semidihedral defect groups up to splendid Morita equivalence. This completes the classification of all principal $2$ -blocks of ta…

math.RT2020

Trivial source endo-trivial modules for finite groups with a semi-dihedral Sylow $2$ -subgroup

Shigeo Koshitani, Caroline Lassueur

We finish off the classification of the endo-trivial modules of finite groups with Sylow $2$ -subgroups isomorphic to a semi-dihedral $2$ -group started by Carlson, Mazza and Thévena…

The Mathieu group M12​ vs SL3​(3) in characteristic 3