∀ (y n n' : ℤ),
  n + y = n' →
    ∀ (p q : ℤ),
      (ComplexShape.up ℤ).π (ComplexShape.up ℤ) (ComplexShape.up ℤ) (p, q) = n →
        (ComplexShape.up ℤ).π (ComplexShape.up ℤ) (ComplexShape.up ℤ) (p, q + y) = n'