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Branch and bound branch and bound methods economize the search for the best trees by backing out of dead alleys.

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Presentation on theme: "Branch and bound branch and bound methods economize the search for the best trees by backing out of dead alleys."— Presentation transcript:

1 Branch and bound branch and bound methods economize the search for the best trees by backing out of dead alleys.

2 The Traveling Salesman Problem the technique can be used to solve the traveling salesman problem.

3 The Traveling Salesman Problem d=5.4342 an arbitrary route.

4 The Traveling Salesman Problem d=2.8027 d=5.4342 greedy, starting from each point

5 The Traveling Salesman Problem d=2.8027 d=5.4342 d=2.7812 solution found by branch and bound

6 The Traveling Salesman Problem start 1 2 3 4 5 6 … 2 3 4 8 9 10 1,2,3,4,5,6,7,8,9,10 10 9 1,2,3,4,5,6,7,8,10,9 9 8 10 1,2,3,4,5,6,7,9,8,10 10 8 1,2,3,4,5,6,7,9,10,8 10 8 9 1,2,3,4,5,6,7,10,8,9 9 8 1,2,3,4,5,6,7,10,9,8 3 4 5 5 6 the problem as a decision tree with 3 628 800 (10!) paths

7 Branching and bounding B&B walk along the paths, and keep track of the distance travelled and the shortest route as yet

8 Branching and bounding distance=x distance>x and bound back out of lengthy paths

9 Branch and bound for parsimony a b c a d b c a c b d a c b d a c b e a c d e c e b d a e b d c a d b e a d c e b a d b e c a d b c e d e b c a e a b c d a e c d b b e c d a a b c d e a b c e d a b d e c a d b c

10 5 8 7 9 9 9 9 9 11 9 10 8 11

11 Branch and bound for parsimony 5 8 7 9 9 9 9 9 11 9 10 8 11

12 Branch and bound for parsimony 5 8 7 9 9 9 9 9 11 9 10 8 11


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