| min(depths(t0, i + 1) + depths(t1, i + 1)) < i, ∀ i. ¬ min(depths(t0, i)) < i, ∀ i. ¬ min(depths(t1, i)) < i ⊦ |
⊦ x ≠ [] ∧ y ≠ [] → min(x + y) = min(min(x), min(y))
⊦ depths(t, i) ≠ []
depths(t0, i + 1) ≠ [] ∧ depths(t1, i + 1) ≠ [], min(min(depths(t0, i + 1)), min(depths(t1, i + 1))) < i, ∀ i. ¬ min(depths(t0, i)) < i, ∀ i. ¬ min(depths(t1, i)) < i ⊦
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (depths(t1, i + 1), depths(t0, i + 1))]]