Queen versus Pawn

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The Queen versus Pawn Endgame (KQKP) is usually won by the queen side, in particular if the queen can occupy the pawn's frontspan. Even if the pawn is ready to promote, supported by its own king, the technique is to come closer with the attacking king, after the defending king was forced to block the promotion square due to a queen check. However, with rook and bishop pawns on the seventh (second) rank, stalemate is looming with the defending king in the corner. There are even some rare cases with center and knight pawns where the attacking king hinders its own queen to give check. =Rook Pawn on 7th= The draw motive is a stalemate threat, after the defending king blocks its own pawn after a queen check on the neighbouring knight file, so that the attacking king can't come closer. A Chebyshev Distance of at least four to the promotion square with a Manhattan distance less than eight for the attacking king is necessary to win that game ( green area below ). While implementing this pattern inside a interior node recognizer, one has to take care that with the king in the corner (i.e. black king on a1), the queen has no mate in one (i.e. on c1).

...Q..../....K.../......../(....)..../(.....).../(.....).../(pk...).../(kk...)... =Bishop Pawn on 7th= A similar draw motive occurs here with stalemate after the queen captured the bishop pawn. The winning area of the attacking king requires a bit more calculation. Critical squares for the Chebyshev Distance are the neighbouring square on the same rank on the luff-side (i.e. for black pawn on c2, &#977;(&#9812;,d2)), and the diagonal neighbouring square on the lee-side one rank back (i.e. for black pawn on c2, &#977;(&#9812;,b3)).
 * With a distance below two to any of these critical squares, the game is won.
 * A distance of two to any of these critical squares is required to win the game if the defending king blocks its pawn
 * Even a distance of two is not sufficient, if the defending king occupies the corner square (i.e. a1), or the 7th/8th (1st/2nd) rank on the neighbouring knight file (i.e. b1, b2).

...Q..../....K.../......../{....}..../(...){...}../(.+...){.}../(.kp+.){.}../kk{k}(..){.}..

=See also=
 * Draw Evaluation
 * Interior Node Recognizer

=Publications=
 * Reuben Fine (1941). Basic Chess Endings. Bell & Sons
 * Karsten Müller, Frank Lamprecht (2001). Fundamental Chess Endings. Gambit Publications
 * Reuben Fine, Pal Benko (2003). Basic Chess Endings. McKay
 * Yasser Seirawan (2003). Winning Chess Endings. Everyman Chess

=Forum Posts=
 * Marcel Duchamp endgame "splits" engines / hash phenomenon by Kenneth Regan, CCC, February 19, 2018 » Chess Problems, Compositions and Studies, Marcel Duchamp, Transposition Table
 * KQKP and the like by Harm Geert Muller, CCC, May 25, 2019

=External Links=
 * Queen versus pawn endgame from Wikipedia
 * Queen vs. Pawn on 7th‎ by TonightOnly, Chess.com, July 12, 2008

=References= Up one Level