2 + m0 + m0 = (2 + 1) + n0 + n0, ∀ m. m + m ≠ n0 + n0 + 1, ∀ n. m0 + m0 ≠ (2 + 1) + n + n ∨ ¬(∀ m. m + m ≠ n + n + 1) ⊦