| buf[n0] = empty, n0 < # buf, ∀ buf. n0 ≤ # buf → datasize(buf, datasize(buf, n0)) = datasize(buf, n0) ⊦ datasize(buf, datasize(buf, n0)) = (buf[n0] = empty ⊃ datasize(buf, n0);n0 + 1) |
buf[n0] = empty, n0 < # buf, ∀ buf. n0 ≤ # buf → datasize(buf, datasize(buf, n0)) = datasize(buf, n0) ⊦ datasize(buf, datasize(buf, n0)) = datasize(buf, n0)