| n > 0, n0 = n ⊦ ⟪tree_buffer_heap_init#(n0; ; H, rxs, rys, h, xs_len, to_delete)⟫ ⟨caterpillar_init#(n; ; h0, xs, xs_len0, ys)⟩ ∃ n. ((ls(rxs, xs) * ls(rys, ys) * del-list(to_delete, n)))(H) ∧ n ≤ # xs + # ys ∧ n + # xs ≤ h ∧ h = h0 ∧ xs_len = xs_len0 |