| ⊦ (sdt[str0, tree] -- str)[str1] = (sdt -- str)[str0, tree][str1], str = str0 |
⊦ str ≠ str0 → (sdt -- str0)[str] = sdt[str]
str1 = str ⊦ (sdt[str0, tree] -- str)[str1] = (sdt -- str)[str0, tree][str1], str = str0
⊦ sdt[str0, tree][str1] = (sdt -- str)[str0, tree][str1], str = str0, str1 = str
Used terms: str1, str, sdt[str0, tree]