| ∀ i, x, t1, y. depths(t, i) + x = depths(t1, i) + y → x = y ∧ t = t1, ∀ i, x, t1, y. depths(t2, i) + x = depths(t1, i) + y → x = y ∧ t2 = t1, depths(Node(t, t2), i) + x = depths(t1, i) + y ⊦ x = y ∧ Node(t, t2) = t1 |
⊦ depths(Node(t0, t1), i) = depths(t0, i + 1) + depths(t1, i + 1)
(depths(t, i + 1) + depths(t2, i + 1)) + x = depths(t1, i) + y, ∀ i, x, t1, y. depths(t, i) + x = depths(t1, i) + y → x = y ∧ t = t1, ∀ i, x, t1, y. depths(t2, i) + x = depths(t1, i) + y → x = y ∧ t2 = t1 ⊦ x = y ∧ Node(t, t2) = t1
[[CONCRETESIMPRULES : ()]]