| i ' + x = (depths(t, i + 1) + depths(t0, i + 1)) + y, i ∈ depths(t, i + 1) ⊦ |
y ≠ [] ⊦ d ' + x = y + z ↔ d = head(y) ∧ x = pop(y) + z
⊦ depths(t, i) ≠ []
depths(t, i + 1) + depths(t0, i + 1) ≠ [], i = head(depths(t, i + 1) + depths(t0, i + 1)) ∧ x = pop(depths(t, i + 1) + depths(t0, i + 1)) + y, i ∈ depths(t, i + 1) ⊦
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ ¬ x + y ≠ [] ↔ x = [] ∧ y = []], [CSIMPSEQ : ⊦ (x + y) + z = x + y + z])], [EXTRATERMS : (y, depths(t, i + 1) + depths(t0, i + 1), x, i)]]