| datasize(buf, n) = (buf[n0] = empty ⊃ datasize(buf, n0);n0 + 1) ↔ (∀ n1. n ≤ n1 ∧ ¬ n0 < n1 → buf[n1] = empty), n < # buf, n ≤ n0, ∀ buf, n. (datasize(buf, n) = datasize(buf, n0) ↔ (∀ n2. n ≤ n2 ∧ n2 < n0 → buf[n2] = empty)) ∧ n < n0 ∧ n < # buf ∧ (∀ n2. n < n2 ∧ n2 < n0 → buf[n2] = empty) → n + 1 = datasize(buf, n0) ∨ buf[n] = empty, ∀ n1. n < n1 ∧ ¬ n0 < n1 → buf[n1] = empty ⊦ n + 1 = (buf[n0] = empty ⊃ datasize(buf, n0);n0 + 1), buf[n] = empty |
datasize(buf, n) = (buf[n0] = empty ⊃ datasize(buf, n0);n0 + 1) ↔ (∀ n1. n ≤ n1 ∧ ¬ n0 < n1 → buf[n1] = empty), buf[n0] = empty, n < # buf, n ≤ n0, ∀ n1. n < n1 ∧ ¬ n0 < n1 → buf[n1] = empty, ∀ buf, n. (datasize(buf, n) = datasize(buf, n0) ↔ (∀ n2. n ≤ n2 ∧ n2 < n0 → buf[n2] = empty)) ∧ n < n0 ∧ n < # buf ∧ (∀ n2. n < n2 ∧ n2 < n0 → buf[n2] = empty) → n + 1 = datasize(buf, n0) ∨ buf[n] = empty ⊦ n + 1 = datasize(buf, n0), buf[n] = empty
datasize(buf, n) = (buf[n0] = empty ⊃ datasize(buf, n0);n0 + 1) ↔ (∀ n1. n ≤ n1 ∧ ¬ n0 < n1 → buf[n1] = empty), n < # buf, n ≤ n0, ∀ n1. n < n1 ∧ ¬ n0 < n1 → buf[n1] = empty, ∀ buf, n. (datasize(buf, n) = datasize(buf, n0) ↔ (∀ n2. n ≤ n2 ∧ n2 < n0 → buf[n2] = empty)) ∧ n < n0 ∧ n < # buf ∧ (∀ n2. n < n2 ∧ n2 < n0 → buf[n2] = empty) → n + 1 = datasize(buf, n0) ∨ buf[n] = empty ⊦ n + 1 = n0 + 1, buf[n] = empty, buf[n0] = empty