typo

main.tex

@@ -13,7 +13,7 @@
 \section{``Cut-free'' Proof}
 \begin{problem}[b-free knapsack]\label{bfreeknap}
     Consider a set of elements $E$ and two weights $w:E\to \Z_+$ and 
-    $c:E\to Z_+$ and a budget $b\in \Z_+$. Given a feasible set $\mathcal 
+    $c:E\to \Z_+$ and a budget $b\in \Z_+$. Given a feasible set $\mathcal 
     F\subset 2^E$, find $\min_{X
     \in \mathcal F, F\subset E} w(X\setminus F)$ such that $c(F)\leq b$.
 \end{problem}