Canonical Fitting_igFun := [igFun by Fitting_sub & morphim_Fitting].
Canonical Fitting_gFun := [gFun by morphim_Fitting].
Canonical Fitting_pgFun := [pgFun by morphim_Fitting].
Section IsoFitting.
Variables (gT rT : finGroupType) (G D : {group gT}) (f : {morphism D >-> rT}).

Lemma simple_sol_prime G : solvable G -> simple G -> prime #|G|.