Project Amendment Number 1

6.170 Handout 29

Handed out on April 5, 1994

1 The UNDO Command

The customer of the antichess program (i.e., your TA) has just noticed that an important requirement was inadvertently dropped from the initial requirements specification. The missing requirement is that an UNDO operation should be available to the human player. The UNDO command allows the human player to take back moves. The UNDO command needs to be enabled only when it is the human player's turn to make a mov. When the UNDO command is issued, the most recent pair of moves is undone, and it will be the human player's turn to move again. The board and the timer clocks revert to the states they had immedi ately b efore the h uman pla y er had his/her last move. The user should be able to back up to the beginning of the game by issuing the UNDO command repeatedly . You must amend the save file format to add extra information, so that the UNDO command can be used on saved games to undo past the point at which the game was saved. However, your program must be downward-compatible , i.e., it must be able to load games in the old format, although the user will not be able to back up past the point of the save in such games.

Project Amendment Number 2

6.170 Handout 30

Handed out on April 14, 1994

The HINT Command

A new command called HINT is b eing added to the antichess program. This command provides the human player with the facility of asking help from the program about the next move the human player can make. The HINT command needs to be enabled only when it is the human player's turn to make a move. The clocks of the human player or the machine player should not be tic king while the program is generating a hint. When the HINT command is issued, the antichess program computes a reasonably good valid move for the human player and displays it on the screen. It is up to you to decide how much time to take for generating this move or how good the move should be. Make sure that you document your design decisions for the HINT command. Your next submission, i.e., the oral presentation, should discuss how you have incorporated the HINT command in your design.

Project Amendment Number 3

6.170 Handout 32

Handed out on April 21, 1994

The FLIP Command

A new command called FLIP is being added to the antichess program. The FLIP command allows the human player to change sides at any time. The human player will still begin a new game playing white, and will move first. On his/her turn, the human player may issue the FLIP command; the human now plays black and the computer plays white. The board position remains the same. The human player should be able to issue the FLIP command as many times during the game as desired, changing sides each time. Note that after the human flips sides, it is the machine player's turn to make a move. It is up to you to decide which clock is to be assigned to the human player after the flip. You may have to make other design decisions to support the FLIP command; be sure to document them.

Spec Amendment

There are some spec amendments to the machine player interface; you must conform to these changes. The game file format is augmented to include the color that the machine player is playing. The format and a sample initial board configuration is shown below.


	<game-file> ::= <machine-player-color> newline
                        <next-turn-color> newline
                        <timeleft> newline <board>



	B W 300.0 300.0 

	rnbqkbnr
	pppppppp
	-------- 
	--------
	--------
	-------- 
	PPPPPPPP
	RNBQKBNR

When a new game is started, the machine player is set to play black. When the board configuration is loaded from a file, the referee must inform the machine player of the color it is supposed to play. Note that this information is already included in the board argument (which corresponds to the game file format) of machine player$reset.