Unmake Move

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Unmake Move is a function inside a chess program to update the internal chess position and its Board representation as well as associated or dependent state variables and data by a move unmade on the internal board. In unmake move, reversible aspects of a position can be incrementally updated by the inverse or own inverse operation of Make Move. Irreversible aspects of a position, such as ep state, castling rights and the halfmove clock are either restored from a stack ( LIFO), or simply kept in arrays indexed by current search or game ply. Alternatively, one may capacitate the move with all the necessary information to recover those irreversible aspects of a position as well.

See also#

• Bitboard Update By Move
• Copy-Make
• Encoding Moves
• Incremental Updates
• Make Move
• Piece-List Update by Unmake Move

Forum Posts#

1998 …#

• Working with moves or with positions by Guillem Barnolas, rgcc, February 22, 1998 » KC Chess
• Unmake move v copy the board by Hugh Cumper, CCC, January 24, 1999
• Move Make/Unmake Questions by Daniel Homan, CCC, July 15, 1999

2000 …#

• Does Unmake Move Really Save Time? by Adrian Jackson, rgcc, March 08, 2001
• UnMakeMove by Orhan Öztürk, rgcc, December 09, 2002
• Why have a UnMakeMove or UndoMove function (not as stupid as it sounds)? by Albert Bertilsson, CCC, February 24, 2003 » Sharper
• The need to unmake move by Mathieu Pagé, CCC, August 19, 2003

2005 …#

• doing undoing by Fritz Reul, CCC, May 14, 2007
• implementation of undoMove()? by cyberfish, CCC, January 26, 2008
• make/unmake by Robert Pope, Winboard Forum, April 08, 2006 » Beaches
• undo move vs. Position Cloning by BoldReceiver, CCC, September 16, 2009
• copy/make vs make/unmake test results by Robert Hyatt, CCC, September 19, 2009 » Crafty

2010 …#

• Copy Board vs Unmake Move by ChrisJ, OpenChess Forum, September 29, 2010
• performance of copy-make by Rein Halbersma, CCC, August 02, 2011
• make and unmake statistics by Fermin Serrano, CCC, February 28, 2012 » Search Statistics
• Make and Unmake implementation by CDaley11, OpenChess Forum, February 01, 2013  » Make Move
• How costly is taking moves back ? by Piotr Lopusiewicz, CCC, April 30, 2013
• copy/make vs make/unmake by Robert Hyatt, CCC, January 07, 2014
• Memory usage in make/unmake vs logic complexity by Matthew Lai, CCC, August 30, 2014

2015 …#

• Unifying make/undo and copy-make by Rein Halbersma, CCC, December 21, 2015
• Copy-make vs Make/Unmake ? by Mahmoud Uthman, CCC, November 12, 2016
• Is Unmake Move truly necessary? by SethCS, Winboard Forum, May 18, 2017

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