| depths(t0, i) + x = depths(t1, i) + y ⊦ x = y ∧ t0 = t1 |
depths(Leaf, i) + x = depths(t1, i) + y ⊦ x = y ∧ Leaf = t1
∀ 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
[[CONCRETESIMPRULES : ([CSIMPGEN : tree generated by leaf, node;])]]