fact: Definition countable_uniformity (T : uniformType) := exists R : set (set (T * T)), [/\ countable R, R `<=` entourage & forall P, entourage P -> exists2 Q, R Q & Q `<=` P].
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed