proposition: Lemma inl_dl_fg_prop1 i l (H:inc l I2): inl_dl_fg i l = (inl_can_fun (inl_dl_S_lambda H) i).
proof: Proof. by rewrite /inl_dl_fg/inl_dl_system_S_lambda; case: (ixm (inc l I2)). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)