D1 January 2005 Q1
1.

The bipartite graph in Figure 1 shows a mapping between six people, Andy (\(A\)), David (\(D\)), Joan (\(J\)), Preety (\(P\)), Sally (\(S\)) and Trevor (\(T\)), and six tasks 1, 2, 3, 4, 5 and 6.
The initial matching is \(A\) to 2, \(D\) to 1, \(J\) to 3 and \(P\) to 4.
(a) Indicate this initial matching in a distinctive way on the bipartite graph drawn in the answer book. (1)
(b) Starting from this initial matching, use the maximum matching algorithm to find a complete matching. List clearly the alternating paths you use. (5)
| Scheme | Marks |
|---|---|
![]() | B1 |
| (1) |
| Scheme | Marks |
|---|---|
| e.g. \(S - 3 = J - 4 = P - 6\) c.s. \(S = 3 - J = 4 - P = 6\) | M1 A1 (2) |
| and \(T - 2 = A - 1 = D - 5\) c.s. \(T = 2 - A = 1 - D = 5\) | M1 A1 |
| \(A = 1\quad D = 5\quad J = 4\quad P = 6\quad S = 3\quad T = 2\) | A1 (3) |
| (5) | |
| (6 marks) |
Notes
c.s. = change status.
