In the sequent calculus version, this is manifestly true because there is no rule that can have "⋅ ⇒ ⊥" as a conclusion!
在相继式演算中，这明显为真，因为没有规则可以有“ ⋅ ⇒ ⊥ {\displaystyle \cdot \Rightarrow \bot } ”作为结论!