proposition: Lemma formZ a u : '[a *: u]= (a * theta a) * '[u].
proof: Proof. by rewrite formZl formZr mulrA. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix mxalgebra vector falgebra ssrnum algC algnum) mathcomp(fieldext) mathcomp(vector)