Assignment 3 Information

• Support code:
  • a3code.com --- support code Version 1.2.2

    Although the extension of this file is "com", it is not a Windows/DOS executable; "com" is simply the extension chosen for compiled Scheme files. The load command in the assign3.scm file will work just fine as it is.

  • a3puzzles.scm --- sliding block puzzles Version 1.1

    I will be adding more puzzles to the next revision of this file.

  • assign3.scm --- a file with "stubs" for your procedures

• Running Scheme with more memory:
  • For running through gnu-emacs, make sure the following is in your .emacs file:

    (load-library "xscheme")
    (setq scheme-program-arguments "-heap 4000")
    

  • From the UNIX command line, just add the above "heap switch" when you start the program.
  • For Edwin on Windows, you need to edit the shortcut or properties to add the same "heap" switch above.

• Errata

• Problem 7, 9, and 10 details

• sbp-child-states Oracle

• Electronic submission information

• Links:
  • The Sliding Block Puzzle Page
  • An introduction to sliding block puzzles
  • An 8-puzzle A* java applet

• [9/20] There is a minor update of the a3code.com file which corrects a small error --- if you give invalid inputs to the valid-move? procedure, it generates an error in its mechanism to generate an error telling you gave it invalid inputs.

• [9/18] The sbp-move procedure, contrary to the documentation in the assignment handout, is of the form: (sbp-move sbp move) where move is a list of the form (block direction) where direction is one of: left, right, up, down.

• [9/18] Version 1.2 of a3code.com is now available. This incorporates some additional error checking as well as other mostly cosmetic changes.

  Version 1.1 of a3puzzles.scm is also now available. It now contains all the puzzles you need for this assignment.

• [9/14] There is no Problem 5 on this assignment.

• [9/14] For problem 8, your procedure should take two arguments instead of one:

    (sbp-heuristic sbp goal-template)
  

  This has been incorporated into the "stub" in the assign3.scm file.

• [9/14] I made a few changes in the printing parameters for the A* code:
  • There is another variable pm-period (with default value of 100) which controls how frequently "progress messages" are printed.
  • The default values of print-moves and print-states was set to #t.