Periodic flat modules, and flat modules for finite groups
Periodic flat modules, and flat modules for finite groups
If R is a ring of coefficients and G a finite group, then a flat RG-module which is projective as an R-module is necessarily projective as an RG-module.More generally, if H is a subgroup of finite index in an arbitrary group Ī, then a flat RĪmodule which is projective as ā¦