proposition: Lemma cfnorm_Ind_cfun1 : H <| G -> '['Ind[G, H] 1] = #|G : H|%:R.
proof: Proof. move=> nsHG; rewrite cfInd_cfun1 // cfnormZ normr_nat cfdot_cfuni // setIid. by rewrite expr2 {2}natf_indexg ?normal_sub // !mulrA divfK ?mulfK ?neq0CG. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype tuple finfun bigop prime order) mathcomp(ssralg poly finset fingroup morphism perm) mathcomp(automorphism quotient finalg action gproduct) mathcomp(zmodp commutator cyclic center pgroup sylow) mathcomp(matrix vector falgebra ssrnum algC algnum) mathcomp(archimedean)