A chess problem, also called a chess composition, is a puzzle set by the composer using chess pieces on a chess board, which presents the solver with a particular task. For instance, a position may be given with the instruction that White is to move first, and checkmate Black in two moves against any possible defence. A chess problem fundamentally differs from over-the-board play in that the latter involves a struggle between Black and White, whereas the former involves a competition between the composer and the solver. Most positions which occur in a chess problem are 'unrealistic' in the sense that they are very unlikely to occur in over-the-board play. There is a good deal of specialized jargon used in connection with chess problems.
In the game of chess, perpetual check is a situation in which one player can force a draw by an unending series of checks. This typically arises when the player who is checking cannot deliver checkmate, and failing to continue the series of checks gives the opponent at least a chance to win. A draw by perpetual check is no longer one of the rules of chess; however, such a situation will eventually allow a draw claim by either threefold repetition or the fifty-move rule. Players usually agree to a draw long before that, however.
A Babson task is a directmate chess problem with the following properties:
- White has only one key, or first move, that forces checkmate in the stipulated number of moves.
- Black's defences include the promotion of a certain pawn to a queen, rook, bishop, or knight.
- If Black promotes, then the only way for White towards a forced checkmate in the stipulated number of moves is to promote a pawn to the same piece to which Black promoted.
This glossary of chess problems explains commonly used terms in chess problems, in alphabetical order. For a list of unorthodox pieces used in chess problems, see Fairy chess piece; for a list of terms used in chess is general, see Glossary of chess; for a list of chess-related games, see List of chess variants.
Grid chess is a chess variant invented by Walter Stead in 1953. It is played on a grid board. This is a normal 64-square chessboard with a grid of lines further dividing it into larger squares. A single additional rule governs Grid chess: for a move to be legal, the piece moved must cross at least one grid line.
Stalemate is a situation in chess where the player whose turn it is to move is not in check and has no legal move. Stalemate results in a draw. During the endgame, stalemate is a resource that can enable the player with the inferior position to draw the game rather than lose. In more complex positions, stalemate is much rarer, usually taking the form of a swindle that succeeds only if the superior side is inattentive. Stalemate is also a common theme in endgame studies and other chess problems.
A helpmate is a type of chess problem in which both sides cooperate in order to achieve the goal of checkmating Black. In a helpmate in n moves, Black moves first, then White, each side moving n times, to culminate in White's nth move checkmating Black. Although the two sides cooperate, all moves must be legal according to the rules of chess.
Checkmate is any game position in chess and other chess-like games in which a player's king is in check and there is no possible escape. Checkmating the opponent wins the game.
A selfmate is a chess problem in which White, moving first, must force the unwilling Black to deliver checkmate within a specified number of moves. Selfmates were once known as sui-mates.
In chess, a pure mate is a checkmate position such that the mated king is attacked exactly once, and prevented from moving to any of the adjacent squares in its field for exactly one reason per square. Each of the squares in the mated king's field is attacked or "guarded" by one—and only one—attacking unit, or else a square which is not attacked is occupied by a friendly unit, a unit of the same color as the mated king. Some authors allow that special situations involving double check or pins may also be considered as pure mate.
The Saavedra position is one of the best-known chess endgame studies. It is named after the Spanish priest Fernando Saavedra (1849–1922), who lived in Glasgow during the late 19th century. Though not a strong player, he spotted a win involving a dramatic underpromotion in a position previously thought to have been a draw.
Karel Traxler was a Czech chess master and composer of chess problems. He is best known for the hyper-aggressive variation named after him, the Traxler Variation in the Two Knights Defense.
The bishop and knight checkmate in chess is the checkmate of a lone king by a king, a bishop, and a knight. With the stronger side to move and with perfect play, checkmate can be forced in at most thirty-three moves from any starting position where the defender cannot quickly win one of the pieces. The exception is the "stalemate trap". These exceptions constitute about 0.5% of the positions. Checkmates are possible with the defending king on any square at the edge of the board but can be forced only from positions with different material or if the defending king is in a corner controlled by the bishop or on a square on the edge next to a corner; however, mate adjacent to the corners not controlled by the bishop is only two moves deep, so it is not generally encountered unless the defending side plays inaccurately. Although this is classified as one of the four basic or elementary checkmates, it occurs in practice only approximately once in every 6,000 games.
In chess, a blunder is a critically bad move or decision. A blunder severely worsens the player's situation by allowing a loss of material, checkmate, or anything similar. It is usually caused by some tactical oversight, whether due to time trouble, overconfidence, or carelessness. Although blunders are most common in beginner games, all human players make them, even at the world championship level. Creating opportunities for the opponent to blunder is an important skill in over-the-board chess.
A joke chess problem is a puzzle in chess that uses humor as a primary or secondary element. Although most chess problems, like other creative forms, are appreciated for serious artistic themes, joke chess problems are enjoyed for some twist. In some cases the composer plays a trick to prevent a solver from succeeding with typical analysis. In other cases, the humor derives from an unusual final position. Unlike in ordinary chess puzzles, joke problems can involve a solution which violates the inner logic or rules of the game.
This article covers computer software designed to solve, or assist people in creating or solving, chess problems – puzzles in which pieces are laid out as in a game of chess, and may at times be based upon real games of chess that have been played and recorded, but whose aim is to challenge the problemist to find a solution to the posed situation, within the rules of chess, rather than to play games of chess from the beginning against an opponent.
Thomas Rayner Dawson was an English chess problemist and is acknowledged as "the father of Fairy Chess". He invented many fairy pieces and new conditions. He introduced the popular fairy pieces grasshopper, nightrider, and many other fairy chess ideas.
The chess endgame of a queen versus pawn is usually an easy win for the side with the queen. However, if the pawn has advanced to its seventh rank it has possibilities of reaching a draw, and there are some drawn positions with the pawn on the sixth rank. This endgame arises most often from a race of pawns to promote.
The Immortal Draw is a chess game played in 1872 in Vienna by Carl Hamppe and Philipp Meitner. This game is the main claim to fame of both Hamppe and Meitner, and has been reprinted widely. The variation of the Vienna Game it uses was named the Hamppe–Meitner Variation in honour of the two players. The game was played in the 19th-century Romantic style, in which rapid development and attack were considered the most effective way to win, where many gambits and countergambits were offered, and where material was often held in contempt. These games, with their rapid attacks and counterattacks, are often entertaining to review even if some of the moves would no longer be considered best by today's standards.
The Traxler Counterattack, also known as the Wilkes-Barre Variation, is a chess opening that begins with the moves:
