proposition: Lemma sup_graph_pr1 r f: order r -> sub (range f) (substrate r) -> has_sup_graph r f -> least_upper_bound r (range f) (sup_graph r f).
proof: Proof. rewrite /has_sup_graph/sup_graph/sup_graphp=> or sr hs; fprops. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)