proposition: Lemma formN u : '[- u] = '[u].
proof: Proof. by rewrite formNr formNl opprK. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix mxalgebra vector falgebra ssrnum algC algnum) mathcomp(fieldext) mathcomp(vector)