| ∀ 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 → (∀ t, x1. x0 ≠ depths(t, i0) + x1))), depths(t, i) + x1 ≠ [], max(depths(t, i) + x1) ≤ i1 + i, 0 ≤ i1, head(depths(t, i) + x1) < i ⊦ |
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ d + x = d ' + x], [CSIMPFORWARD : ⊦ depths(t, i) + x = d ' + y → d ∈ depths(t, i)], [CSIMPSEQ : ⊦ (x + y) + z = x + y + z], [CSIMPFORWARD : ⊦ d ' + x = y → d ∈ y], [CSIMPSEQ : ⊦ d ' + x ≠ []], [CSIMPSEQ : ⊦ d ∈ x → d ∈ x + y], [CSIMPSEQ : ⊦ d ∈ depths(t, i) → (d < i ↔ false)], [CSIMPELIM : x ≠ [] ⊦ d = head(x) ∧ y = pop(x) ↔ x = d + y])], [EXTRATERMS : (depths(t, i) + x1, d, y)]]