| x2 = x, x ≠ [], max(x) < 0 ⊦ 〈build_rec#(0; x, to)〉 〈to0 := to, x0 := x ; if x0 ≠ [] then to0 := fail〉 (to0 ≠ fail → x2 = depths(to0 .t, 0)) |
⊦ i ∈ x → i ≤ max(x)
x2 = x, x ≠ [], max(x) < 0, head(x) ∈ x → head(x) ≤ max(x) ⊦ 〈build_rec#(0; x, to)〉 〈to0 := to, x0 := x ; if x0 ≠ [] then to0 := fail〉 (to0 ≠ fail → x2 = depths(to0 .t, 0))
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (head(x), x)]]