Edexcel D1 2013 January — Question 3 8 marks

Exam BoardEdexcel
ModuleD1 (Decision Mathematics 1)
Year2013
SessionJanuary
Marks8
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicMatchings and Allocation
TypeMaximum matching algorithm application
DifficultyModerate -0.3 This is a standard application of the maximum matching algorithm from D1, requiring students to follow a well-defined procedure (finding alternating paths) with minimal conceptual challenge. Part (b) requires identifying why complete matching is impossible (likely a Hall's marriage theorem violation), which adds slight difficulty, but overall this is a routine algorithmic question below average difficulty for A-level.
Spec7.02a Graphs: vertices (nodes) and arcs (edges)7.02g Eulerian graphs: vertex degrees and traversability

3. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{bd6edbd4-1ec0-4c7e-bd39-b88f96bf52fb-3_743_625_758_269} \captionsetup{labelformat=empty} \caption{Figure 2}
\end{figure} \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{bd6edbd4-1ec0-4c7e-bd39-b88f96bf52fb-3_746_608_758_1142} \captionsetup{labelformat=empty} \caption{Figure 3}
\end{figure} Figure 2 shows the possible allocations of six workers, Charlie (C), George (G), Jack (J), Nurry (N), Olivia (O) and Rachel (R), to six tasks, \(1,2,3,4,5\) and 6. Figure 3 shows an initial matching.
  1. Starting from this initial matching, use the maximum matching algorithm to find an improved matching. You should give the alternating path you use and list your improved matching.
  2. Explain why it is not possible to find a complete matching. After training, Charlie adds task 5 to his possible allocations.
  3. Taking the improved matching found in (a) as the new initial matching, use the maximum matching algorithm to find a complete matching. Give the alternating path you use and list your complete matching.

3.

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{bd6edbd4-1ec0-4c7e-bd39-b88f96bf52fb-3_743_625_758_269}
\captionsetup{labelformat=empty}
\caption{Figure 2}
\end{center}
\end{figure}

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{bd6edbd4-1ec0-4c7e-bd39-b88f96bf52fb-3_746_608_758_1142}
\captionsetup{labelformat=empty}
\caption{Figure 3}
\end{center}
\end{figure}

Figure 2 shows the possible allocations of six workers, Charlie (C), George (G), Jack (J), Nurry (N), Olivia (O) and Rachel (R), to six tasks, $1,2,3,4,5$ and 6.

Figure 3 shows an initial matching.
\begin{enumerate}[label=(\alph*)]
\item Starting from this initial matching, use the maximum matching algorithm to find an improved matching. You should give the alternating path you use and list your improved matching.
\item Explain why it is not possible to find a complete matching.

After training, Charlie adds task 5 to his possible allocations.
\item Taking the improved matching found in (a) as the new initial matching, use the maximum matching algorithm to find a complete matching. Give the alternating path you use and list your complete matching.
\end{enumerate}

\hfill \mbox{\textit{Edexcel D1 2013 Q3 [8]}}