3 Five towns, 1, 2, 3, 4 and 5, are connected by direct routes as shown. The arc weights represent distances.
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- The printed answer book shows the initial tables and the results of iterations \(1,2,3\) and 5 when Floyd's algorithm is applied to the network.
(A) Complete the two tables for iteration 4.
(B) Use the final route table to give the shortest route from vertex 5 to vertex 2.
(C) Use the final distance table to produce a complete network with weights representing the shortest distances between vertices. - Use the nearest neighbour algorithm, starting at vertex \(\mathbf { 4 }\), to produce a Hamilton cycle in the complete network. Give the length of your cycle.
- Interpret your Hamilton cycle from part (ii) in terms of towns actually visited.
- Find an improved Hamilton cycle by applying the nearest neighbour algorithm starting from one of the other vertices.
- Using the complete network of shortest distances (excluding loops), find a lower bound for the solution to the Travelling Salesperson Problem by deleting vertex 4 and its arcs, and by finding the length of a minimum connector for the remainder. (You may find the minimum connector by inspection.)
- Given that the sum of the road lengths in the original network is 43 , give a walk of minimum length which traverses every arc on the original network at least once, and which returns to the start. Show your methodology. Give the length of your walk.