proposition: Lemma setring_fin_bigcup : fin_bigcup_closed <<r G>>.
proof: Proof. by apply/fin_bigcup_closedP; split; [apply: setring0|apply: setringU]. Qed.
imports: mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality fsbigop ) reals ereal signed topology normedtype sequences esum numfun HB(structures)