CS440: Assignment #6
Assigned Oct. 3rd
Due 12:30, Oct. 17th

A* Search---Programming Assignment

• Implement A* search for searching trees. Do not use Russell's code.
• Add a counter that counts the number of nodes expanded and prints this number when the search concludes.
• Use your A* code to solve the two-jugs problem discussed in class.
• Solve the jugs problem these four ways by specifying h and g:
  • uniform-cost search
  • limited depth-first search (can do this by setting cost very high once it hits the limit)
  • A* using h1, a heurisitic function given in class
  • A* using h2, a second heuristic function given in class
• Write a lisp function that returns the effective branching factor, given the number of nodes expanded and the depth of the goal (number of states in the solution path).
• Calculate the effective branching factor for the jugs problem solved using the four ways listed above.
• Write the code needed by your A* code to solve the maze problem discussed in class, using the given start and goal states and the placement of walls.
• Write a function as described in class to display the maze and the solution path.
• Using the results of the previous two items, find the shortest path and display it.
• Now do this again, but find the solution path with the fewest number of direction changes, by changing the action cost function.

Please turn in printouts of your lisp code and examples of your code running correctly. Also, type or write neatly an explanation of your lisp code. You must write at least one sentence for each lisp function you write and more than one sentence for long functions that cannot be cleary explained in one sentence. Please put your name and student number at the top of the first page and staple multiple pages together.

Also, e-mail to me a single file that contains everything needed to complete the items requested above. Be sure to include calls to your functions for solving the problems. I will run these myself to check that they actually run. Be sure you check your file first before you e-mail it to me.