proposition: Lemma eq_bigcapl T U A B (F : T -> set U) : A <--> B -> \bigcap_(x in A) F x <--> \bigcap_(x in B) F x.
proof: Proof. by move => H a; split; move => Ha b Hb; eapply Ha; eapply H; eauto. Qed.
imports: mathcomp.ssreflect.ssreflect Classes.RelationClasses Classes.Morphisms List Tactics mathcomp(ssrfun ssrbool ssrnat seq)