Editing Cross-check (chess)

In [[chess]], a '''cross-check''' (or '''counter-check''') is a [[Chess tactics|tactic]] in which a [[check (chess)|check]] is played in response to a check, especially when the original check is blocked by a [[chess piece|piece]] that itself either delivers check or reveals a [[discovered check]] from another piece. Sometimes the term is extended to cover cases in which the [[King (chess)|king]] moves out of check and reveals a [[discovered check]] from another piece (this is also known as a ''royal check''); it does not generally apply to cases where the original checking piece is captured.

The cross-check is an essential tactic in winning some [[chess endgame|endgames]] such as those with two [[queen (chess)|queens]] versus one, or a [[queen and pawn versus queen endgame|queen and pawn versus a queen]].  In these cases, the defense usually tries for a [[perpetual check]] and sometimes the stronger side can stop it only by a cross-check.
{{algebraic notation|pos=tocleft}}

==Examples==
A cross-check occurs from time to time in games.  It is an essential [[chess tactic|tactic]] in winning [[chess endgame|endgames]] such as two [[queen (chess)|queens]] versus one queen, or queen and [[pawn (chess)|pawn]] versus queen, where it is used to stop a series of checks from the opponent and force the [[Exchange (chess)|exchange]] of queens.  It is also used in some [[chess problem]]s.

===Botvinnik vs. Minev game===
{{Chess diagram
| tright
|Botvinnik vs. Minev, 1954
|  |  |  |  |  |  |  | 
|  |  |xo|  |  |  |pl| 
|  |  |oo|  |  |  |  | 
|  |  |kl|ql|  |  |  | 
|kd|  |oo|oo|  |  |  | 
|  |  |  |  |  |  |  | 
|  |  |xo|  |  |xo|  |qd
|  |  |  |  |  |  |xo| 
|Black, to move, resigned. Black dots are where the black queen can check; white dots are where the white queen can cross-check in reply.
}}

Cross-checks are rare in actual play, though they do occur, and in some [[Chess endgame|endgames]], particularly [[Queen (chess)|queen]] endgames, they are very important. The position shown to the right is the final position in the famous queen endgame from the game <ref>[http://www.chessgames.com/perl/chessgame?gid=1032347 Botvinnik vs. Minev]</ref> between [[Mikhail Botvinnik]] and [[Nikolay Minev]], Amsterdam Olympiad, 1954. In the position shown, after '''91. Kc5!!''', Black [[List of chess terms#Resign|resigned]] because the promising looking checks 91...Qc7+, 91...Qg1+, 91...Qf2+ and 91...Qc2+ are answered by the cross-checks 92.Qc6+, 92.Qd4+, 92.Qd4+ and 92.Qc4+ respectively, forcing an exchange of queens in all cases, which will result in the [[promotion (chess)|promotion]] of the [[Pawn (chess)|pawn]] and winning the game by a basic [[checkmate]]. This is an important theme in queen endgames: the weaker side often gives a series of checks, and it is frequently important for them to avoid simplifying cross-checks such as these in reply {{Harvcol|Burgess|2000|pp=102–3, 458–59}}, {{Harvcol|Golombek|1977}}. If the black queen attacks the pawn instead of checking it does no good since the promotion square of the pawn is protected by its queen. Note too that if Black instead merely allows the pawn's promotion, another cross-check may be necessary to win, as in the next section.
{{clear left}}

===Two queens versus one===
{{Chess diagram
|tleft
|Botvinnik vs. Ravinsky, 1944
|  |  |qd|  |  |  |  | 
|  |  |  |  |  |  |pl| 
|  |  |  |  |  |  |kl| 
|  |  |  |  |  |  |  | 
|kd|  |  |  |  |ql|  | 
|  |  |  |  |  |  |  | 
|  |  |  |  |  |  |  | 
|  |  |  |  |  |  |  | 
|Black resigned after 126.Qf4+.
}}
{{Chess diagram
|tleft
|Possible continuation
|  |qd|  |  |oo|kl|  | 
|  |  |  |  |ql|ql|  | 
|  |  |  |  |  |  |  | 
|  |  |  |  |  |  |  | 
|kd|  |  |  |  |  |  | 
|  |  |  |  |  |  |  | 
|  |  |  |  |  |  |  | 
|  |  |  |  |  |  |  | 
|Cross-check with 135.Qee8+ wins.
}}
{{clear}}
In the position on the left from Botvinnik–Ravinsky,<ref>[http://www.chessgames.com/perl/chessgame?gid=1032089 Botvinnik vs. Ravinsky]</ref> Black resigned.  With best play according to the [[endgame tablebase]], 126...Kb3 127.Qf7+ Ka4 128.g8=Q Qg4+ 129.Kh6 Qh4+ 130.Kg7 Qg3+ 131.Kf8 Qd6+ 132.Qe7 Qh6+ 133.Qgg7 Qf4+ 134.Qgf7 Qb8+ and the position on the right is reached.  Then the cross-check 135.Qee8+ (or Qfe8+) [[fork (chess)|forks]] the king and queen, forces an exchange, and wins the game.

===Anderson problem, 1919===
{{Chess diagram
| tright
|G.F. Anderson, 1919
|  |  |  |  |  |  |  | 
|  |  |kl|  |ql|pd|  |bd
|  |  |pd|  |  |  |  | 
|  |kd|  |  |  |  |  | 
|  |  |  |  |  |  |  | 
|rl|bl|pd|  |  |  |rd| 
|  |  |  |  |  |  |  | 
|  |rl|  |  |  |  |  | 
|}}

Cross-checks are relatively infrequent in actual play, but are popular in [[chess problem]]s since they make for a relatively unobvious solution. In the problem shown to the right, White is to move and mate in two moves against any defence. It is by [[Gerald Frank Anderson|G.F. Anderson]] and was first published in ''Il Secolo'' in 1919. The [[chess problem terminology#K|key]] 1.Kd6, threatening 2.Qb7#, gives the black king two [[flight square]]s, and two of the variations exploit these: 1...Kb6 2.Bc2# and 1...Kb4 2.Kxc6#. The other two defences exploit the fact that the key exposes the white king to checks, and are answered by cross-checks: 1...Rg6+ 2.Be6# and 1...Rd3+ 2.Bd5#.
{{clear}}

===Anderson problem, 1961===
{{Chess diagram
| tright
|G. F. Anderson, ''[[The Observer]]'', 1961
|  |  |  |ql|  |bd|  |nd
|rd|  |  |  |pd|  |  |kl
|pd|  |pl|pl|pl|pl|  |pd
|rl|  |nl|  |kd|nd|  |rd
|  |  |bl|  |  |rl|pl| 
|  |  |  |  |pd|  |bl|nl
|  |  |  |  |  |pd|  |qd
|  |bd|  |  |  |  |  | 
|}}
The problem to the right, also by G. F. Anderson (first published in ''[[The Observer]]'' in 1961) and also a mate in two, features no fewer than five cross-checks. The key is 1.Qb6 (threat: 2.Ne4#), with the following variations:

:1...exf6+ 2.Nb7#
:1...exd6+ 2.Nd7#
:1...Nd4+ 2.Rf5#
:1...Nxd6+ 2.Nd3#
:1...Nf-other+ 2.Ne4#
:1...Kxf6 2.Qb2#
:1...Kxd6 2.Rd4#
{{clear left}}

==See also==
* [[Pawnless chess endgame]]

==References==
{{reflist}}

'''Bibliography'''
* {{citation
| last=Burgess| first=Graham|authorlink = Graham Burgess
| title=The Mammoth Book of Chess
| publisher=Carroll & Graf Publishers
| year=2000
| edition = 2nd
| isbn= 0-7867-0725-9}}
* {{citation
   | last=Golombek | first=Harry |author-link=Harry Golombek
   | year=1977
   | title=Golombek's Encyclopedia of Chess
   | publisher=Crown Publishing
   | isbn=0-517-53146-1 }}
* {{citation
 | last=Hooper | first=David  | authorlink=David Vincent Hooper
 | last2=Whyld | first2=Kenneth | authorlink2=Kenneth Whyld
 | title=[[The Oxford Companion to Chess]]
 | year=1992
 | edition=second
 | publisher=Oxford University Press
 | isbn=0-19-280049-3 }}

==Further reading==
* John Rice, ''Chess Wizardry: The New ABC of Chess Problems'' (London, Batsford, 1996)

==External links==
* [http://www.chessgames.com/perl/chessgame?gid=1063968 Three successive cross-checks in a game]

{{chess}}

{{DEFAULTSORT:Cross-Check}}
[[Category:Chess terminology]]
[[Category:Chess problems]]
[[Category:Chess tactics]]