proposition: Lemma max_elt_seq1 : max_elt r a -> max_elt (r ⨾ r') a.
proof: Proof. unfold seq; red; ins; desf; apply H in REL; desf; eauto. Qed.
imports: HahnBase HahnList HahnSets HahnRelationsBasic HahnEquational HahnRewrite Arith Setoid