# nσ = ⌜m1⌝ + ⌜1⌝ , stutf(nσ) ⊦ (∃ m. ¬ m1 < m ∧ nσ[m] = nσ[m1]) ∧ (¬ m1 < m0 ∧ nσ[m0] = m - 1 → ¬ nσ[m1] + 1 < m)