typo; closes #424

Author: rzach

content/first-order-logic/tableaux/proof-theoretic-notions.tex

@@ -102,7 +102,7 @@
 \{\sFmla{\False}{!B}, & \sFmla{\True}{!A}, \sFmla{\True}{!C_1},
 \dots, \sFmla{\True}{!C_n}\}
 \intertext{has a closed !!{tableau}. If $\Gamma \Proves !A$ then there
-  are $!D_1$, \dots, $!D_m$ such that}
+  are $!D_1$, \dots, $!D_m \subseteq \Gamma$ such that}
 \{\sFmla{\False}{!A}, & \sFmla{\True}{!D_1},
 \dots, \sFmla{\True}{!D_m}\}
 \end{align*}