On the other hand, ∀ x x → {\displaystyle \forall x\,x\rightarrow } is not a formula, although it is a string of symbols from the alphabet.
另一方面， ∀ x x → {\displaystyle \forall x\,x\rightarrow } 則不是公式，雖然這也是由詞彙表中的符號組成的字串。