| ∀ j0, i0, x, x0, to. i→n(j0 - i0) < i→n(i1) → (x = x0 ∧ x0 ≠ [] ∧ i0 ≤ j0 ∧ max(x0) ≤ j0 → 〈build_rec#(i0; x, to)〉 (to ≠ fail → x0 = depths(to .t, i0) + x)), x = x0, x0 ≠ [], max(x0) ≤ i1 + i, 0 ≤ i1, x2 = x ∧ d0 = i, h0 = head(x2), h0 < d0 ⊦ 〈to0 := fail〉 (to0 ≠ fail → x0 = depths(to0 .t, i) + x2) |
[[CONCRETESIMPRULES : ()]]