| n + m ≤ # buf0 + # buf1, n + m ≤ # buf0 ⊦ (∀ n2. n ≤ n2 ∧ n2 < n + m → (buf0 + buf1)[n2] = empty) ↔ (∀ n2. n ≤ n2 ∧ n2 < n + m → buf0[n2] = empty) |
n + m ≤ # buf0, n + m ≤ # buf0 + # buf1, ∀ n2. n ≤ n2 ∧ n2 < n + m → (buf0 + buf1)[n2] = empty ⊦ ∀ n2. n ≤ n2 ∧ n2 < n + m → buf0[n2] = empty
n + m ≤ # buf0, n + m ≤ # buf0 + # buf1, ∀ n2. n ≤ n2 ∧ n2 < n + m → buf0[n2] = empty ⊦ ∀ n2. n ≤ n2 ∧ n2 < n + m → (buf0 + buf1)[n2] = empty