| ⊦ m < # kar ∧ valid-idx(kar, ar, m + 1) ∧ kar[m] = key-index(key, m1) → valid-idx(kar[m0, key-index(key, m1)], ar[m1, ar[m1].idx:= m0], m) |
kar[m] = key-index(key, m1), m < # kar, valid-idx(kar, ar, m + 1) ⊦ valid-idx(kar[m0, key-index(key, m1)], ar[m1, ar[m1].idx:= m0], m)