Fix typo in Section 22.11 of the Open Logic Text

Author: FnControlOption

content/first-order-logic/axiomatic-deduction/provability-quantifiers.tex

@@ -27,7 +27,7 @@
 \begin{proof}
 By the deduction theorem, $\Gamma \Proves \ltrue \lif !A(c)$. Since
 $c$ does not occur in $\Gamma$ or~$\top$, we get $\Gamma \Proves
-\ltrue \lif !A(c)$. By the deduction theorem again, $\Gamma \Proves
+\ltrue \lif \lforall[x][!A(x)]$. By the deduction theorem again, $\Gamma \Proves
 \lforall[x][!A(x)]$.
 \end{proof}