proposition: Lemma Vfilter_head_true : forall n (bs : bools (S n)) x (v : vec n) (h : Vhead bs = true), Vfilter bs (Vcons x v) = Vcast (Vcons x (Vfilter (Vtail bs) v)) (Vtrue_Sn_true bs h).
proof: Proof. intros. apply Vfilter_head_true_eq. hyp. Qed.
imports: Coq(Arith) CoLoR(VecUtil LogicUtil EqUtil)