Complete State Space Search

1. Draw the complete state space search graph for the farmer, wolf, goat, and cabbage problem. Indicate the paths that are discarded due to constraint violations or duplicate nodes.

2. Determine whether goal-driven or data-driven search would be preferable for each of the following problems. Justify your answer.

a. Diagnosing mechanical problems in an automobile.

b. You have met a person who claims to be your distant cousin, with a common ancestor John Doe. You would like to verify her claim.

c. Another person claims to be your distant cousin. He does not know the common ancestor’s name but knows that it was no more than eight generations back. You would like to either find this ancestor or determine that she does not exist.

d. A theorem prover for plane geometry.

e. A program for examining sonar readings and interpreting them, such as telling a large submarine from a small submarine from a whale from a school of fish.

f. An expert system that will help a human classify plants by species, genus, etc.

3. a. A search procedure finds a solution at level 10 with a penetrance of 0.005. What is the effective branching factor and approximate number of nodes that are examined?

b. An alternative search procedure has an effective branching factor of 1.4. What is the penetrance and number of nodes examined using the alternative?

4. a. Use the alpha-beta search algorithm to determine the best move and the expected gain (or loss) for the each of the game trees shown in Figure A on the next page. Assume that the tree is searched from left to right. Indicate the branches which are pruned by the alpha-beta process.

b. Repeat step a using Figure B.

c. Repeat step b (Figure B) searching the tree from right to left. Explain the differences in your results.