Fifo and lido search algo presentation

1. Fifo search and Lifo search

2. Branching and Bounding
B & B requires TWO tools:
1. Way of covering the feasible solution by several smaller feasible solution
called BRANCHING.
2. BOUNDING is a way of finding upper and lower bound for the optimal
solution within a feasible sub –solution.
If the lower bound of a sub-problem A form the search tree is greater than the
upper bound for any other previously examined sub-problem B,than
May be safely discarded from the search. This is called PRUNING.

3. ANSWER NODE: those solution state S for which path from root to S defines a tuple which is a member of the
set of (i.e., it satisfies the implicit constraints ) of the problem.
LIVE NODE:A node which has been generated and all of those children have not yet been generated is live
node.
E-NODE:The live node whose children are currently being generated is called the E-node (node being
expanded).
DEAD NODE:It is generated node that is either not to be expanded further or one for which all of its children
have been generated.

4. Generally THREE types of searching strategies used in Branch and Bound :
1.FIFO(first in first out)search
2.LIFO(last in first out)search
3.LC(least cost)search

5. FIFO SEARCH
• BFS with QUEUE based Branch &Bound is called FIFO Branch &Bounding.
• In FIFO search the children of the root node are generated in the first iteration.
• In the next step,children of the first child is generated.
• If the children not alredy killed by bounding function then put it in the queue. Then the children of
second child is explored.
• Put all the children in the queue except for those children which are killed.
• FIFO refers to a QUEUE Data Structures.

6. SOURCE
DESTINATION
1
2 3
4
4
2
8
20
1
2 3 4
3
4
2 4
4 4
10 15 20
4 8
4 2
2 8
10 15

7. LIFO SEARCH
LIFO (last in first out) search
• DFS with stack based Branch & Bound is called LIFO Branch &Bound.
• In LIFO search the children of the root node are generated in the first iteration.
• int the next step, children of the first child is generated.
• If the children not already killed by bounding function then putbit in the stack.Then the children of
second child is explored.
•
• Put all the children in the stack except for those children which are killed.