proposition: Lemma inf_graph_pr1 r f: order r -> sub (range f) (substrate r) -> has_inf_graph r f -> greatest_lower_bound r (range f) (inf_graph r f).
proof: Proof. rewrite /has_inf_graph/inf_graph/inf_graphp; fprops. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)