Affiliation:
1. Department of Pure Mathematics, Faculty of Mathematical Sciences, Shahrekord University, Shahrekord, Iran
Abstract
For a finite group G, let Z(G) denote the center of G and cs*(G) be the set
of non-trivial conjugacy class sizes of G. In this paper, we show that if G
is a finite group such that for some odd prime power q ? 4, cs*(G) =
cs*(PGL2(q)), then either G ? PGL2(q) X Z(G) or G contains a normal subgroup
N and a non-trivial element t ? G such that N ? PSL2(q)X Z(G), t2 ? N and G = N. ?t?. This shows that the almost simple groups cannot be determined by
their set of conjugacy class sizes (up to an abelian direct factor).
Publisher
National Library of Serbia