fact: Definition cons_inj {A} {a1 a2} {n} {v1 v2 : t A n} (eq : a1 :: v1 = a2 :: v2) : a1 = a2 /\ v1 = v2 := match eq in _ = x return caseS _ (fun a2' _ v2' => fun v1' => a1 = a2' /\ v1' = v2') x v1 with | eq_refl => conj eq_refl eq_refl end.
imports: VectorDef PeanoNat Eqdep_dec