proposition: Lemma injectiveP : reflect (injective f) injectiveb.
proof: Proof. by apply: (iffP (dinjectiveP _)) => injf x y => [|_ _]; apply: injf. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(path div)