- Perpetual check
In the game of
chess , perpetual check is a situation in which one player can force a draw by an unending series of checks. Such a situation typically arises when the player who is checking cannot delivercheckmate , while any other move gives the opponent a chance to win. Perpetual check is no longer one of therules of chess . However, such a situation will eventually result in a draw by eitherthreefold repetition or thefifty move rule , but usually players agree to a draw harvcol|Burgess|2000|p=478.Perpetual check can also occur in other
chess variant s, although the rules relating to it may be different. For example, giving perpetual check is not allowed (an automatic loss for the giver) in bothshogi andxiangqi .Examples
Chess diagram|=
tright
=8 | | | | | | |kd| |=7 | | | | | |pd|pd| |=6 | | |ql| | | | |pd|=5 | | | | | | | | |=4 | | | | | | | | |=3 | | | | | |pl| |pl|=2 |rd| | |qd| | |pl| |=1 | | | | | | |kl| |=
White to move gets a draw by perpetual check, starting with 1. Qc8+.In this diagram, Black is ahead a rook, which would normally be a decisive material advantage. But White, to move, can draw by perpetual check:: 1. Qc8+ Kh7: 2. Qf5+ Kg8 (or 2... Kh8): 3. Qc8+ Kh7: 4. Qf5+ g6: 5. Qxf7+ Kh8: 6. Qf8+ Kh7: 7. Qf7+ etc.
Unzicker-Averbakh
Chess diagram|=
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Unzicker-Averbakh
=8 | | | | | |rd|kd| |=7 | |rd|pl| | | |pd|pd|=6 |pd| | | | |nd| | |=5 | | | |pl|pd| | | |=4 | |pl| | |pl|qd| | |=3 | | |ql| | | | |pl|=2 |pl| | | | | |pl| |=1 |rl| | | |rl| |kl| |= a b c d e f g h
Perpetual check extricates Black from his difficulties.In the second diagram, from Unzicker-Averbakh,
Stockholm Interzonal 1952 , [http://www.chessgames.com/perl/chessgame?gid=1153024] Black (on move) would soon be forced to give up one of his rooks for White's c-pawn (to prevent it from promoting or to capture the promoted queen after promotion). He can, however, exploit the weakness of White's kingsidepawn structure with :1... Rxc7!:2. Qxc7 Ng4! (threatening 3...Qh2#) :3. hxg4 Qf2+ salvaging a draw by threefold repetition with checks on h4 and f2.Hamppe-Meitner
Chess diagram|=
tright
Hamppe-Meitner
=8 |rd| |bd|kd| | | |rd|=7 | | |pd| | |pd|pd|pd|=6 | |pd|kl| | | | | |=5 |pd| | |pd|pd| | | |=4 | | | | | | | | |=3 |pl| | | | | | | |=2 | |pl|pl|pl| | |pl|pl|=1 |rl| |bl|ql| | |nl|rl|= a b c d e f g h
Down massive amounts of material, Black forces a draw by perpetual check.In the classic game Hamppe-Meitner,
Vienna 1872 , [http://www.chessgames.com/perl/chessgame?gid=1250160] following a series of sacrifices Black forces the game to the position in the diagram, a perpetual check: :16...Bb7+!:17.Kb5 (17.Kxb7?? Kd7 18.Qg4+ Kd6 followed by ...Rhb8#) :17...Ba6+:18.Kc6 (18.Ka4?? Bc4 and 19...b5#) :18...Bb7+ ½-½Leko-Kramnik
Chess diagram|=
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Leko-Kramnik, Corus, 2008
=
rd| | | | | | |kd|=
pd|pd| | | | |pd|pd|=
| |pd| | | | | |=
| | | | |ql| | |=
| | | | | | |pl|=
| |qd| | | | | |=
| |pl| | |pl|pl| |=
|kl| |rl| | | |rl|=
Position after 24. Qxf5.In the game betweenPeter Leko andVladimir Kramnik at the 2008 Corus tournament, Black was able to obtain a draw because of perpetual check::24... Qb4+:25. Ka2 Qa4+:26. Kb2 Qb4+:27. Kc1 Qa3+:28. Kb1 ½–½
Fischer-Tal
Chess diagram|=
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Fischer-Tal, Leipzig, 1960
=
| |kd| | | | | |=
pd|pd| | |nd| | |ql|=
| | | |qd| | | |=
pl| | |pd| | | | |=
| | | | | | | |=
pl| |pd| | | | | |=
| |pl| | |pl|kl|pl|=
| | | | |rl| | |=
Position after 21. Kh1xg2.A perpetual check saved a draw for
Mikhail Tal againstBobby Fischer in this 1960 game, played in the14th Chess Olympiad , while Tal was the World Champion. Now Black played 21... Qg4+ and the game was drawn Harvcol|Evans|1970|p=53. (After 22. Kh1 then 22... Qf3+ 23. Kg1 Qg4+ forces perpetual check.)History
Chess diagram|=
tright
N.N.-Unknown
=8 |rd| |bd| | | | | |=7 |pd|pd|pd| | |bl|pd|kd|=6 | | | |pd| | |nl|pd|=5 | | | | |pd| | | |=4 | | | | |pl| | |qd|=3 | | | |pl| |nd| |pl|=2 |pl|pl|pl| | |bd|pl| |=1 |rl| |bl| | | | |kl|= a b c d e f g h
Final positionThe "Oxford Encyclopedia of Chess Games, Volume 1 (1485-1866)" includes all recorded games played up to 1800 Harvcol|Levy|O'Connell|1981|p=ix. The earliest example of perpetual check contained in it is a game played by two unknown players in 1750: N.N.-Unknown, 1750 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.0-0 (the rules of
castling not yet having been standardized in their current form, White moved his king to h1 and his rook to f1) Nf6 5.Nc3 Ng4 6.d3 0-0 (Black moved his king to h8 and his rook to f8) 7.Ng5 d6 8.h3 h6 9.Nxf7+ Rxf7 10.Bxf7 Qh4 11.Qf3 Nxf2+ 12.Rxf2 Bxf2 13.Nd5 Nd4 14.Ne7 Nxf3 15.Ng6+ Kh7 ½-½ in light of 16.Nf8+ Kh8 17.Ng6+ etc. Harvcol|Levy|O'Connell|1981|p=9 The next examples of perpetual check in the book are two games, both ending in perpetual check, played in 1788 between Bowdler and Philidor, with Philidor giving odds ofpawn and move Harvcol|Levy|O'Connell|1981|p=12.A draw by perpetual check used to be in the
rules of chess Harvcol|Reinfeld|1954|p=175.Howard Staunton gave it as one of six ways to draw a game in "The Chess-Player's Handbook" harvcol|Staunton|1847|p=21–22. It has since been removed since perpetual check will eventually allow a draw claim by eitherthreefold repetition or thefifty move rule . If a player demonstrates intent to perform perpetual check, the players usually agree to a draw harvcol|Hooper|Whyld|1992|.ee also
*
Rules of chess
*Desperado
*Stalemate References
*citation
last=Burgess |first=Graham |authorlink = Graham Burgess
title=The Mammoth Book of Chess
publisher=Carroll & Graf
year=2000
edition = 2nd
id=ISBN 978-0-7867-0725-6* Citation
surname1=Evans|given1=Larry|authorlink1=Larry Evans
title=Modern Chess Brilliancies
year=1970
publisher=Fireside
ID=ISBN 0-671-22420-4
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surname1=Hooper|given1=David|authorlink1=David Vincent Hooper
surname2=Whyld|given2=Kenneth|authorlink2=Kenneth Whyld
title=The Oxford Companion to Chess
year=1992
edition=second
publisher=Oxford University Press
ID=ISBN 0-19-866164-9
* Citation
surname1=Levy|given1=David|authorlink1=David Levy
surname2=O'Connell|given2=Kevin|authorlink2=
title=Oxford Encyclopedia of Chess Games, Volume 1 (1485-1866)
year=1981
edition=
publisher=Oxford University Press
ID=ISBN 0-19-217571-8
* Citation
surname1=Reinfeld|given1=Fred|authorlink1=Fred Reinfeld
title=How To Be A Winner At Chess
year=1954
publisher=Fawcett
ID=ISBN 0-449-91206-X
*citation
last=Speelman|first=Jon|authorlink=Jon Speelman
year=1981
title=Endgame Preparation
publisher=Batsford
id=ISBN 0-7134-4000-7
* citation
surname1=Staunton | given1=Howard | authorlink1=Howard Staunton
year=1847
title=The Chess-Player's Handbook
location=London | publisher=H. G. Bohn
pages=21–22 (1985 Batsford reprint, ISBN 1-85958-005-X)External links
* [http://www.chessvariants.com/d.chess/eternal.html Diagram demonstrating a perpetual check]
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