[GAP Forum] Decomposing rational modules

[Gabor Ivanyos]

Dear Dima, Willem, Peter, all,
> Formulae for this can be found in Serre's book "Linear representations
> of finite groups." Springer GTM, Vol. 42.
I think Peter was asking for decomposition over Q. Let us stress "over Q"`.
I agree Willem in that it is hard in general. For finite groups it mght be ber
somewhat easier than the general case, but I am not aware of any serious
result supportimg this.
Gabor