| str ∈ sdt, p0 ∈ sdt[str], ∀ tree. p0 ∈ tree → tree[p0].fids ⊆ tree.fids ⊦ sdt[str][p0].fids ⊆ sdt.fids |
⊦ str ∈ sdt ↔ (∃ tree, sdt0. sdt = sdt0[str, tree] ∧ ¬ str ∈ sdt0)
p0 ∈ sdt[str], ∀ tree. p0 ∈ tree → tree[p0].fids ⊆ tree.fids, ∃ tree, sdt0. sdt = sdt0[str, tree] ∧ ¬ str ∈ sdt0 ⊦ sdt[str][p0].fids ⊆ sdt.fids
Used terms: sdt, str