| str < str2, str2 < str3 ⊦ str < str3 |
∀ str2, str3. str0 < str2 ∧ str2 < str3 → str0 < str3, char + str0 < str2, str2 < str3 ⊦ char + str0 < str3
Used simplifier rules: less-empty: ⊦ "" < str ↔ str ≠ "";%Less-notempty: ⊦ ¬ str < "";%string freely generated by "", +;;