| ⊦ sdt[str0, tree] -- str = (sdt -- str)[str0, tree], str = str0 |
⊦ sdt1 = sdt2 ↔ (∀ str. (str ∈ sdt1 ↔ str ∈ sdt2) ∧ sdt1[str] = sdt2[str])
⊦ str = str0, ∀ str1. (str1 ∈ sdt[str0, tree] -- str ↔ str1 ∈ (sdt -- str)[str0, tree]) ∧ (sdt[str0, tree] -- str)[str1] = (sdt -- str)[str0, tree][str1]
Used terms: (sdt -- str)[str0, tree], sdt[str0, tree] -- str