proposition: Lemma bigcap_seq r F : \bigcap_(i <- r) F i = \bigcap_(i in r) F i.
proof: Proof. by apply: setC_inj; rewrite !setC_bigcap bigcup_seq. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop)