proposition: Lemma derivableX f n (x v : V) : derivable f x v -> derivable (f ^+ n.+1) x v.
proof: Proof. by move/derivableP. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrnum matrix interval) mathcomp(mathcomp_extra boolp classical_sets functions) reals signed topology prodnormedzmodule normedtype landau forms