proposition: Lemma nthCircPerm2Eq {T:Type} {n:nat} : forall (cp : cartesianPower T (S (S n))) (Default : T) id, id <= n -> nthCP (S (S id)) cp Default = nthCP (S id) (consTailCP (tailCP cp) (headCP cp)) Default.
proof: Proof. intros cp Default id Hle. apply nthCircPerm2. reflexivity. assumption. Qed.
imports: Arith NArith List Sorting Coq.Program.Equality