small fix in implem

new_system3.tex

@@ -679,7 +679,7 @@ rules, because one branch is already unreachable and retyping only occurs with s
   \Gamma_\circ\bvdash{a}{\Gammap(x)}\{\Gamma_i\}_{i\in I}\\
   \forall i\in I.\ \Gamma_\circ\subst{x}{\Gamma_\circ(x)\land\Gammap(x)}\avdash{(\Gammap\land\Gamma_i)\setminus\{x\}}{[]} \ct[\letexp x a e] : \tree_i}
   {
-  \Gamma\avdash\Gammap\ct\letexp x a e : \Node(\Gamma,\{(\{\}, \tree_i)\}_{i\in I})
+  \Gamma\avdash\Gammap\ct\letexp x a e : \Node(\Gamma_\circ,\{(\{\}, \tree_i)\}_{i\in I})
   }
   { }
 \end{mathpar}