A Cluster tilting module for a representation-infinite block of a group algebra

TL;DR

This paper demonstrates the existence of a 3-cluster tilting module in a specific representation-infinite block of a group algebra, providing a novel example in the field of algebra representation theory.

Contribution

It presents the first known example of a representation-infinite block of a group algebra with a cluster tilting module, answering a longstanding question.

Findings

Existence of a 3-cluster tilting module in the principal block of KG

First example of a representation-infinite block with a cluster tilting module

Addresses a question posed by Erdmann and Holm

Abstract

Let $G=SL(2,5)$ be the special linear group of $2 \times 2$-matrices with coefficients in the field with $5$ elements. We show that the principal block over a splitting field $K$ of characteristic two of the group algebra $KG$ has a $3$-cluster tilting module. This gives the first example of a representation-infinite block of a group algebra having a cluster tilting module and answers a question by Erdmann and Holm.