On the Prime Graph Question for Integral Group Rings of 4-primary groups II

Abstract

In this article the study of the Prime Graph Question for the integral group ring of almost simple groups which have an order divisible by exactly $4$ different primes is continued. We provide more details on the recently developed "lattice method" which turns out to involve the calculation on Littlewood-Richardson coefficients. We apply the method obtaining results complementary to those previously obtained using the HeLP-method. In particular the "lattice method" is applied to infinite series of groups for the first time. We also prove the Zassenhaus Conjecture for four more simple groups.