proposition: Lemma differentiable_Rinv (x : R) : x != 0 -> differentiable (GRing.inv : R -> R) x.
proof: Proof. by move=> xn0; apply/diff_locallyP; rewrite diff_Rinv //; apply: dinv. 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