16S34 11 group ring 8 16U60 6 16S35 4 group rings 4 integral group ring 4 unit group 4 20F19 3 05E20 2 13E10 2 16W20 2 20C05; 20D08 2 20C07 2 20F17 2 94B05 2 94B15 2 Galois algebras 2 Galois extensions 2 Kaplansky conjecture 2 Kimmerle conjecture 2 Zassenhaus conjecture 2 artinian modules 2 commutative 2 complement 2 direct decomposition 2 direct product 2 formation 2 group algebra 2 group algebras 2 group ring codes 2