| tree[parent(p0)].dir?, p0 ∈ tree, tree[p0].fids ⊆ tree.fids ⊦ p0 = ε, sdt0.fids ∪ ((tree.fids ∪ tree1.fids) \ tree[p0].fids) = ((sdt0.fids ∪ tree.fids) ∪ tree1.fids) \ tree[p0].fids, str ∈ sdt0, tree[p0].fids ⊆ tree.fids ∪ tree1.fids |
⊦ fidb ⊆ fidb0 ↔ (∀ fid. count(fid, fidb) ≤ count(fid, fidb0))
tree[parent(p0)].dir?, p0 ∈ tree, ∀ fid. count(fid, tree[p0].fids) ≤ count(fid, tree.fids) ⊦ p0 = ε, sdt0.fids ∪ ((tree.fids ∪ tree1.fids) \ tree[p0].fids) = ((sdt0.fids ∪ tree.fids) ∪ tree1.fids) \ tree[p0].fids, str ∈ sdt0, tree[p0].fids ⊆ tree.fids ∪ tree1.fids
Used terms: tree.fids, tree[p0].fids