(** Treating flip: can't make them direct instances as we need at least a [flip] present in the goal. *)

Lemma flip1 `(subrelation A R' R) : subrelation (flip (flip R')) R.
Ltac proper_reflexive :=
match goal with
| [ _ : normalization_done |- _ ] => fail 1
| _ => class_apply proper_eq || class_apply @reflexive_proper
end.