| ⊦ pos(char1, str) < # str → (pos(char1, str) = pos(char2, str) ↔ char1 = char2) |
pos(char1, str) = pos(char2, str), pos(char2, str) < # str ⊦ char1 = char2, str = ""
Used simplifier rules: len-zero: ⊦ # str = 0 ↔ str = "";%lf-02: ⊦ m < n ∧ m = n0 → n0 < n; (forward) from specification nat-basic1%f: ⊦ m < n → n ≠ 0; (forward) from specification nat-basic1