(** *** [rel_top] *)
(** We used to only have an [RIntro] instance for [⊤%rel], which is enough for proving all goals of the form [⊤%rel x y] but not enough to derive properties of relations in which [⊤%rel] is a component. *)

Lemma rel_top_component_trsym:
forall {A} (x y z: list A),
list_rel ⊤ x y -> list_rel ⊤ z y -> list_rel ⊤ x z.