proposition: Lemma nat_rect_O_arr P Q fO fS x : nat_rect (fun n => P n -> Q n) fO fS 0 x = fO x.
proof: Proof. reflexivity. Qed.
imports: Coq.ZArith.ZArith Coq.Lists.List Coq.Setoids.Setoid Coq.Classes.Morphisms Coq.QArith.QArith_base Coq.QArith.Qreduction Coq.QArith.Qround