fact: Definition set_f_is_lub d (T : porderType d) (set_f : set T -> T) := forall S, ubound S (set_f S) /\ forall x, ubound S x -> set_f S <= x.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype choice order) mathcomp(ssrnat bigop classical_sets)