proposition: Lemma inj_right_composeC (a b c:Set) (f:a->b) (f':b->c): injectiveC (f' \o f) -> injectiveC f.
proof: Proof. by move=> ci x y sv; apply: ci; rewrite !composeC_ev sv. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)