| ∀ str. sdt0[str] = (∅)[str] ∨ str ∈ sdt0 ⊦ sdt0[str0, tree][str] = (∅)[str], str ∈ sdt0[str0, tree] |
∀ str. sdt0[str] = (∅)[str] ∨ str ∈ sdt0 ⊦ sdt0[str] = (∅)[str], str = str0, str ∈ sdt0
Used simplifier rules: ⊦ str ≠ str0 → sdt[str0, tree][str] = sdt[str]; (s)% ⊦ str ∈ sdt[str0, tree] ↔ str = str0 ∨ str ∈ sdt; (ws)