| ⊦ n0 ≤ # buf ∧ n0 = n1 + align↑(datasize(buf, n0), EB_PAGE_SIZE) → subarray(buf, align↑(datasize(buf, n0), EB_PAGE_SIZE), n1) = mkempbuf(n1) |
n0 = n1 + align↑(datasize(buf, n0), EB_PAGE_SIZE), n0 ≤ # buf ⊦ subarray(buf, align↑(datasize(buf, n0), EB_PAGE_SIZE), n1) = mkempbuf(n1)