PERFECT ISOMETRY GROUPS FOR CYCLIC GROUPS OF PRIME ORDER

Abstract

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 information about the block that is also preserved by

a perfect isometry. The structure of this group depends on the block and

can be fairly simple or extremely complicated. In this paper we study

the perfect isometry group for the block of Cp, the cyclic group of prime

order, and completely describe the structure of this group. The result

shows that any self perfect isometry for Cp is essentially either induced

by an element in Aut(Cp), or obtained by multiplication by one of its

linear characters, or a composition of both.