Stalemate

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Stalemate occurs if the side to move is not in check but has no legal moves. Stalemate results in a draw instead of losing the game if in check, and it is likely to occur in late endings only, where it is a regular resource that can enable the player with the inferior position to draw the game, i.e. in KPK or KQKP with rook pawn or bishop pawn on the seventh rank.

In others contexts, the word stalemate is also used for a metaphor when a conflict resolution seems difficult or impossible, i.e. a lose-lose situation.

=Detecting Stalemate= Like checkmate, stalemate is usually determined by the search if it turns out a node above the horizon becomes a terminal node without any further child nodes. It further depends on whether move generation relies on pseudo-legal moves or strictly legal moves.

Pseudo-legal move generation requires trying moves, to find at least one legal move or not, while legal move generation determines the information in advance. In late endings, static evaluation or interior node recognizer may support stalemate detection specially in quiescence search, for instance if there are no legal king moves, pawns are rammed or blocked and other pieces are pinned. =Desperado= Often there are tactical motives associated with so called Desperados, where pieces seem determined to give itself up to bring up stalemate if it is captured.

WMCCC 1993
At the WMCCC 1993 in Munich, round 8, The King found an amazing drawing combination in the game against Nimzo Guernica due to the rook desperados, to either give perpetual check forcing a threefold repetition, or to stalemate : [Event "WMCCC 1993"] [Site "Munich, Germany"] [Date "1993.11.06"] [Round "8"] [White "The King"] [Black "Nimzo Guernica"] [Result "1/2-1/2"]

1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bg5 e6 7.f4 Be7 8.Qf3 Qc7 9.O-O-O Nbd7 10.Bd3 b5 11.Kb1 b4 12.Nce2 Bb7 13.Rhe1 h6 14.Bxf6 Bxf6 15.Qe3 Qc5 16.Qg1 g5 17.Nb3 Qxg1 18.Rxg1 Bd8 19.Nd2 Nc5 20.Rgf1 O-O 21.Nd4 a5 22.fxg5 Bxg5 23.N4b3 Nxd3 24.cxd3 Rfc8 25.Nd4 d5 26.e5 a4 27.Nc2 b3 28.axb3 Ba6 29.Rf3 Bxd2 30.Rxd2 axb3 31.Na3 Bb5 32.d4 Ba4 33.Rf6 Kg7 34.Rd3 Rc7 35.Rg3+ Kh7 36.Rgf3 Kg7 37.Rf1 Rb8 38.R6f3 Rd8 39.h4 Rdc8 40.g4 Rb8 41.g5 hxg5 42.Rg3 Kh6 43.Rxg5 Be8 44.Rgg1 f5 45.exf6 Bg6+ 46.Ka1 Rb4 47.h5 Bf5 48.Rf3 Rf7 49.Rfg3 Rxf6 50.Rh1 Be4 51.Rhg1 Rf8 52.Rh3 Bf5 53.Rf3 Ra8 54.Rf2 Rxd4 55.Re2 Kxh5 56.Rh2+ Rh4 57.Rhg2 d4 58.Rg5+ Kh6 59.Rh5+ Kxh5 60.Rg5+ Kh6 1/2-1/2

nTCEC 1,2
Almost 20 years later, at TCEC Season 5, Stage 1, Spark, already with a huge winning score, became victim of a Delphil's desperado [Event "TCEC - Stage 1 - Season 5"] [Site "http://www.tcec-chess.net"] [Date "2013.09.02"] [Round "3.13"] [White "Delphil 3"] [Black "Spark 1"] [Result "1/2-1/2"]

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O b5 6.Bb3 Bc5 7.Nxe5 Nxe5 8.d4 Bxd4 9.Qxd4 d6 10.f4 Nc6 11.Qd3 O-O 12.Bd2 Be6 13.Nc3 Bxb3 14.cxb3 Re8 15.Rac1 Nb4 16.Qf3 Nc6 17.Be1 Nd4 18.Qd3 b4 19.Nd5 Nxd5 20.Qxd4 Nf6 21.Bh4 c5 22.Qd3 Re6 23.Rc4 a5 24.f5 Re8 25.Rd1 Qe7 26.Bg3 Qb7 27.Bxd6 Rad8 28.e5 Rxe5 29.Bxe5 Rxd3 30.Rxd3 Qe7 31.Re3 h6 32.h3 Nd7 33.Rce4 Nxe5 34.Rxe5 Qd6 35.Re2 Kh7 36.R5e4 Qd3 37.Kh2 h5 38.g3 Kh6 39.g4 hxg4 40.hxg4 Kg5 41.Re1 a4 42.bxa4 c4 43.R4e2 Kxg4 44.Rg1+ Kf3 45.Reg2 Qd6+ 46.Rg3+ Ke4 47.Rf1 Qd2+ 48.Rg2 Qh6+ 49.Kg1 Qe3+ 50.Kh2 c3 51.Rff2 Kd4 52.Rf1 Qe4 53.bxc3+ bxc3 54.Rff2 Kc5 55.Kg3 Kb6 56.Rh2 Qxa4 57.Rc2 Qe4 58.Rhf2 Ka5 59.Rfe2 Qd3+ 60.Kf4 f6 61.Rf2 Kb4 62.Rc1 Qd4+ 63.Kf3 Qc5 64.Kg2 Qd5+ 65.Kg3 Qe5+ 66.Rf4+ Ka5 67.Rc2 Qe1+ 68.Kh3 Qe3+ 69.Kg4 Kb6 70.Rff2 Kc5 71.a4 Kb6 72.Rfe2 Qd3 73.Kf4 Ka5 74.Ra2 Qb1 75.Rf2 Qh1 76.Rfe2 Qd5 77.Kg4 Qf7 78.Kf4 Qc7+ 79.Kf3 Qd6 80.Kg4 Qc5 81.Kf4 Qc4+ 82.Kg3 Qb3 83.Kg4 Qd5 84.Kf4 Qd4+ 85.Kf3 Qh4 86.Rf2 Qh1+ 87.Kf4 Qe1 88.Kg4 Qe3 89.Kh4 g5+ 90.fxg6 Qg5+ 91.Kh3 Qxg6 92.Rg2 Qh5+ 93.Kg3 Qg5+ 94.Kf3 Qh4 95.Ke3 f5 96.Rgc2 Qe4+ 97.Kf2 Qd3 98.Kg2 f4 99.Kf2 Qg3+ 100.Kf1 f3 101.Rf2 Qg4 102.Rac2 Qh5 103.Kg1 Kxa4 104.Ra2+ Kb4 105.Rfc2 Qg4+ 106.Kh2 Qh4+ 107.Kg1 Qg3+ 108.Kh1 Kc4 109.Rxc3+ Kxc3 1/2-1/2

=See also=
 * Checkmate
 * Check
 * Contempt Factor
 * Desperado (chess engine)
 * Draw Evaluation
 * Fifty-move Rule
 * Insufficient Material
 * Repetitions
 * Standing Pat in Quiescence Search

=Forum Posts=

2000 ...

 * Shortest Stalemate by Samuel Loyd by Ed Schröder, CCC, March 02, 2001
 * Nice Stalemate Trap by Tinker by Dieter Bürssner, CCC, October 29, 2001
 * Stalemate trap(SOS-Delfi) by George Lyapko, Winboard Forum, December 18, 2001 » Test-Positions, SOS, Delfi
 * How to handle EGTB stalemates by Tom Likens, CCC, March 02, 2003 » Endgame Tablebases

2005 ...

 * CQL - Stalemate with 2 pieces pinned by James Constance, CCC, July 17, 2005
 * Detecting stalemate with a pseudo-legal movegenerator? by Frederik Tack, CCC, November 11, 2005
 * How to check for checkmate/stalemate programmatically? by Valentin, Rybka Forum, November 22, 2008 » Checkmate

2010 ...

 * Patt-Bug, Junior 11.1a show mate and Ktulu 9.03 made patt! by Frank Quisinsky, CCC, March 23, 2010 » Junior, Ktulu
 * The unavoidable stalemate by Mike Scheidl, CCC, April 24, 2011
 * estimating the number of possible stalemates in perft(n) by Uri Blass, CCC, February 18, 2012 » Perft
 * Yace - Tinker 2001 -> 55.Rxg7?? by Vincent Lejeune, CCC, July 12, 2012
 * Draw by stalemate (Campbell, easy position for engines) by Jesús Muñoz, CCC, July 31, 2013 » Chess Problems, Compositions and Studies
 * stalemate detection and pruning by Jon Dart, CCC, September 22, 2013 » Pruning

2015 ...

 * Request for engines with modified stalemate values by Arno Nickel, CCC, April 16, 2015
 * static mate/stalemate detection? by Alexandru Mosoi, CCC, November 21, 2015 » Null Move Test-Positions, Zugzwang
 * How do you signal stalemate in iterative deepening? by Kenneth Jones, CCC, February 17, 2016 » Iterative Deepening
 * Surprisingly difficult stalemate problem (for some engines) by Juha Nieminen, CCC, May 16, 2016
 * Rabid rook escape by Henk van den Belt, CCC, June 23, 2016

=External Links=
 * Checkmate/Stalemate Scoring from Bruce Moreland's Programming Topics
 * Stalemate from Wikipedia
 * Stalemate! by Jack O’Keefe, July 1999, © 1999 Michigan Chess Association
 * Stalemate by Edward Winter (1999, with updates)
 * Stalemate: the long and the Short of it by H. Paul Lillebo, ChessBase News, August 2, 2014
 * Stalemate: the long and the Short of it – part 2 by H. Paul Lillebo, ChessBase News, August 23, 2014
 * Stalemate: the long and the Short of it (3) by H. Paul Lillebo, ChessBase News, September 22, 2014

=References=

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