proposition: Lemma form_eq0P {u v} : reflect ('[u, v] = 0) (u _|_ v).
proof: Proof. by rewrite normalE; apply/eqP. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix mxalgebra vector falgebra ssrnum algC algnum) mathcomp(fieldext) mathcomp(vector)