| ∀ sdt0, fid. # sdt0 < # sdt → true → (fid ∈ sdt0.fids ↔ (∃ str, p. str ∈ sdt0 ∧ p ∈ sdt0[str] ∧ sdt0[str][p] = fnode(fid))) ⊦ fid ∈ sdt.fids ↔ (∃ str, p. str ∈ sdt ∧ p ∈ sdt[str] ∧ sdt[str][p] = fnode(fid)), sdt = ∅ |
⊦ sdt = ∅ ↔ ¬(∃ str, tree, sdt0. sdt = sdt0[str, tree] ∧ ¬ str ∈ sdt0)
∀ sdt0, fid. # sdt0 < # sdt → true → (fid ∈ sdt0.fids ↔ (∃ str, p. str ∈ sdt0 ∧ p ∈ sdt0[str] ∧ sdt0[str][p] = fnode(fid))) ⊦ fid ∈ sdt.fids ↔ (∃ str, p. str ∈ sdt ∧ p ∈ sdt[str] ∧ sdt[str][p] = fnode(fid)), ∀ str, tree, sdt0. ¬(sdt = sdt0[str, tree] ∧ ¬ str ∈ sdt0)
Used terms: sdt