Remove unused equation number

chapters/2_background.tex

@@ -74,14 +74,14 @@ the model.
 
   The following set of equations describe this knapsack problem as a \gls{cop}:
 
-  \begin{equation}
+  \begin{equation*}
     \text{maximise}~z~\text{subject to}~
     \begin{cases}
       S \subseteq T \\
       z = \sum_{i \in S} joy(i) \\
       \sum_{i \in S} space(i) < C \\
     \end{cases}
-  \end{equation}
+  \end{equation*}
 
   In these equations \(S\) is set \gls{variable}. It contains the selection of
   toys that will be packed for the trip. \(z\) is the objective \gls{variable}