(** [ForallPairs] implies [ForallOrdPairs]. The reverse implication is true only when [R] is symmetric and reflexive. *)

(* Specifications: *)
Lemma ForallPairs_ForallOrdPairs l: ForallPairs l -> ForallOrdPairs l.
Lemma ForallOrdPairs_ForallPairs :
(forall x, R x x) ->
(forall x y, R x y -> R y x) ->
forall l, ForallOrdPairs l -> ForallPairs l.