A

• Actual play - see post-key play.
• Albino
  Albino (chess)
  An Albino is a chess problem in which, at some stage in the solution, a White pawn standing on its starting square makes each of its four possible moves: one square forward, two squares forward, capture to the left, and capture to the right...
  
  - a problem in which, at some point in the solution, a white pawn on its starting square makes each of its four possible moves (forward one square, forward two squares, capture to the left, capture to the right). If the same behaviour is exhibited by a black pawn, it is a Pickaninny.
• Allumwandlung
  Allumwandlung
  Allumwandlung is a chess problem where, at some stage in the solution, the pawn is promoted variously to a knight, bishop, rook and queen....
  
  - a problem in which the solution includes pawn promotions to all possible pieces (in orthodox chess, to bishop, knight, rook and queen; in fairy chess, possibly to fairy pieces).
• Anti-Bristol - the interference of one black piece by another like-moving one on the same line (if the pieces are on different lines, it is a Holzhausen).
• Anticipation - if the theme and setting of a particular problem has already appeared in an earlier problem without the knowledge of the later composer, the problem is said to be anticipated. The position does not have to be exactly the same, just very similar. Where this is done deliberately by the later composer, the term plagiarised is used. There is a real chance of anticipation if the problem has a relatively simple theme, since there are only a finite number of positions and themes, and chess problems have been composed for hundreds of years. However, anticipations are not always noticed immediately.
• Aristocrat - a problem which has no pawn
  Pawn (chess)
  The pawn is the most numerous and weakest piece in the game of chess, historically representing infantry, or more particularly armed peasants or pikemen. Each player begins the game with eight pawns, one on each square of the rank immediately in front of the other pieces...
  
  s in the initial position.

B

• Babson task
  Babson task
  The Babson task is a kind of chess problem of the form "white to move and mate black in N moves against any defence" with the following play:#White makes his first move.#Black defends by promoting a pawn to queen, rook, bishop or knight....
  
  - a problem in which black promotion defences to all possible pieces are answered by white promotions to the same piece black has promoted to. An extreme form of Allumwandlung
  Allumwandlung
  Allumwandlung is a chess problem where, at some stage in the solution, the pawn is promoted variously to a knight, bishop, rook and queen....
  
  .
• Battery - a pair of pieces, where the front piece moves away to discover an attack from the back piece. For example, if a White knight stands between a White rook and the Black king, moving the knight - that is, "firing" the battery - leads to check.
• Block - a problem in which the key provides no threat, but instead puts black in a position of zugzwang
  Zugzwang
  Zugzwang is a term usually used in chess which also applies to various other games. The term finds its formal definition in combinatorial game theory, and it describes a situation where one player is put at a disadvantage because he has to make a move when he would prefer to pass and make no move...
  
  , where every move leads to a mate. In a complete block, all of black's moves have mates provided in the set play and the key is simply a waiting move; in an incomplete block, not all black moves are provided with mates in the set play - the key provides for those that don't; in a mutate some of the mates provided in the set play are changed following the key.
• By-play - variations not directly connected to the problem's theme.

C

• Clearance - in general, the movement of one piece so that another can move to a particular square. In square vacation the first piece moves so that the second can occupy the square on which it stood; in line vacation the first piece moves so that the second can pass over the square on which is stood on the way to its destination; line clearance, also known as the Bristol, is a particular type of line vacation in which a piece moves along a line so that another piece can move a shorter distance behind it along the same line.
• Composition - A constructed position (as opposed to a position found in a game) serving as a Chess problem
  Chess problem
  A chess problem, also called a chess composition, is a puzzle set by somebody using chess pieces on a chess board, that presents the solver with a particular task to be achieved. For instance, a position might be given with the instruction that White is to move first, and checkmate Black in two...
  
  .
• Cook - a second key move, unintended by the composer. A cook is a serious flaw, and invalidates a problem. The publication of cooked problems was once common, but in the modern era computers can be used to check for cooks, and cooked problems are rarely published.
• Cylindrical board - a board in which the a and h-files are considered to be connected (a "vertical cylinder") or the first and eighth ranks are connected (a "horizontal cylinder"). A combination of the vertical and horizontal cylinders is called an "anchor ring".

D

• Directmate - a type of problem where white, moving first, is required to checkmate black in a specified number of moves against any defence. Such a problem is usually indicated by the stipulation "mate in two" (or however many moves is necessary) or "checkmate in two". The term directmate is useful to distinguish these sorts of problems from helpmates, selfmates, reflexmates and others.
• Domination
  Domination (chess)
  In chess, and particularly in endgame studies, domination occurs when a piece has a relatively wide choice of destination squares, but nevertheless cannot avoid being captured....
  
  - in studies, a situation whereby a piece has relatively wide freedom of movement but which nevertheless must be lost.
• Doubling - a manoeuvre in which two pieces are placed on the same line (rank, file or diagonal) such that they support each other. Special cases are Turton doubling and Zepler doubling.
• Dual - ideally, white should have only one move at each juncture which solves a problem - if white has an alternative at any stage other than the first move, this is a dual. A dual is not as serious a flaw as a cook, and in minor lines, duals may be permissible (opinions differ on this point). Some problems make a virtue out of dual avoidance - of two apparently equivalent white moves, only one works.
• Duplex - a type of problem in which there are two solutions, the second one reversing the roles of the colours in the first. The most common type is the duplex helpmate, in which the two solutions to be found are: black moves first and cooperates with white to be mated; and white moves first and cooperates with black to be mated.

E

• Economy - economy is generally regarded as a good thing in chess problem composition, though exactly what is meant by it, and exactly what it is most important to be economical with, is open to debate. Economy of material or force (not using more pieces than necessary), economy of space (using the chessboard to its fullest, not cramming all the pieces into one corner) and economy of motivation (keeping all lines in the solution relevant to the theme) are all regarded as important.
• Excelsior - a problem in which a pawn on its starting square in the initial position moves the length of the board to be promoted during the course of the solution. Named after one such problem by Sam Loyd
  Sam Loyd
  Samuel Loyd , born in Philadelphia and raised in New York, was an American chess player, chess composer, puzzle author, and recreational mathematician....
  
  ; see Excelsior (chess problem)
  Excelsior (chess problem)
  "Excelsior" is one of Sam Loyd's most famous chess problems, originally published in London Era in 1861, named after the poem "Excelsior" by Henry Wadsworth Longfellow. Loyd had a friend who was willing to wager that he could always find the piece which delivered the principal mate of a chess problem...
  
  .

F

• Fairy chess - chess played with non-orthodox rules. Examples are circe, maximummers, problems with unorthodox pieces (fairy pieces) and problems with unorthodox boards (such as cylindrical boards, or grid boards).
• Flight (square) - a square to which the black king can legally move (that is, one not guarded by a white piece, and not occupied by a black piece). If black plays a piece to one of these squares, thus decreasing the king's mobility, it is a self-block. If he moves a piece from one of these squares, it is square-vacation.

G

• Grid-board - a kind of board used in fairy chess which is divided into a grid of 16 2x2 squares. For a move to be legal, the moving piece must pass over at least one of these grid-lines.
• Grimshaw
  Grimshaw (chess)
  A Grimshaw is a device found in chess problems in which two black pieces arriving on a particular square mutually interfere with each other. It is named after the 19th century problem composer Walter Grimshaw....
  
  - a common device featuring two black pieces mutually interfering with each other on a single square.
• Grotesque
  Grotesque (chess)
  In chess, a grotesque is a problem or endgame study which features a particularly unlikely initial position, especially one in which White fights with a very small force against a much larger black army. Grotesques are generally intended to be humorous....
  
  - a problem or study with an especially unnatural initial position, particularly one with large amounts of material or with a large material disparity between the sides.

H

• Heavy - adjective applied to a problem which has a relatively large number of pieces in the initial position. Heaviness should be avoided where possible in the interests of economy.
• Helpmate
  Helpmate
  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...
  
  - a type of problem where white and black cooperate to put black in mate within a specified number of moves. Unless otherwise specified, black moves first in helpmates. See also duplex.
• Holzhausen
  Holzhausen
  Holzhausen may refer to:Places*in Germany:**Holzhausen, Saxony-Anhalt, a municipality in the district of Stendal, Saxony-Anhalt**Holzhausen an der Haide, a municipality in the Rhein-Lahn district, Rhineland-Palatinate...
  
  - the interference of one black piece by another like-moving one on a different line (if the pieces are on the same line, it is an anti-Bristol).

I

• Ideal mate - a pure mate in which all units of both colours take part in the mate.
• Interference
  Interference (chess)
  Interference occurs when the line between an attacked piece and its defender is interrupted by sacrificially interposing a piece. It is a chess tactic which seldom arises, and is therefore often overlooked...
  
  - the closure of the line of one piece by a second piece, thus limiting its movement and cutting it off from certain squares. Various names are given to particular types of interference, among them Grimshaw
  Grimshaw
  -Art:*John Atkinson Grimshaw, Victorian-era painter*Nicholas Grimshaw, English architect*Grimshaw Architects, British Architecture firm-Chess:*Walter Grimshaw, 19th century composer of chess problems...
  
  , Novotny, anti-Bristol, Holzhausen, Würzburg-Plachutta and Plachutta
  Plachutta
  The Plachutta is a device found in chess problems: a white piece sacrifices itself on a square where it could be captured by one of two similarly-moving black pieces moving along a different line; whichever black piece captures, it interferes with the other...
  
  .

K

• Key - the first move of a solution. A problem which unintentionally has more than one key is said to be cooked.

• Knight's tour
  Knight's tour
  The knight's tour is a mathematical problem involving a knight on a chessboard. The knight is placed on the empty board and, moving according to the rules of chess, must visit each square exactly once. A knight's tour is called a closed tour if the knight ends on a square attacking the square from...
  
  - A chess problem where a knight on an empty board has to visit each square exactly once.

L

• Lacny
  Lacny
  The Lacny or Lacny cycle is a chess problem theme named after Ľudovít Lačný, the first person to demonstrate the idea in 1949.It is an example of lines of play being cyclically related: in one phase of play, the Black defences a, b and c are answered by the White mates A, B and C respectively; in...
  
  - a theme in which defences a, b and c are answered by the mates A, B and C respectively in one phase of play and by B, C and A respectively in another.
• Light - adjective applied to a problem which has a relatively small number of pieces in the initial position. Lightness is usually desirable in the interests of economy.

M

• Maximummer - a problem in which black must make the geometrically longest moves available to him, as measured from square-centre to square-centre. If two or more longest moves of equal length are available, black may choose between them. This stipulation is most often attached to selfmates.
• Meredith - a problem with no less than eight and no more than twelve pieces on the board in the starting position. A problem with less than eight pieces is a miniature.
• Miniature - a problem with no more than seven pieces on the board in the initial position.
• Model mate
  Model mate
  A model mate is a type of pure mate checkmating position in chess in which not only is the checkmated king and all vacant squares in its field attacked only once, and squares in the king's field occupied by friendly units are not also attacked by the mating side , but all units of the mating side A...
  
  - a pure mate in which all white units, with the possible exception of king and pawns, are involved in the mate. A particular feature of problems by members of the Bohemian School.
• More-mover - a directmate with the stipulation "white to move and checkmate black in no more than n moves against any defence" where n is greater than 3. In composition tourneys, there are often separate classes for more-movers, two-movers and three-movers (as well as classes for helpmates, selfmates and others).
• Motif
  Motif (chess composition)
  In chess composition, a motif is basic element of a move in the consideration why the piece moves and how it supports the fulfillment of a stipulation. Any move may and often does contain multiple motifs...
  
  - an element of a move in the consideration why the piece moves and how it supports the fulfillment of the problem stipulation.
• Mutate - a type of block problem in which at least one mate in the set play is changed following the key.

N

• Novotny - a sacrificed white piece can be taken by two differently-moving black pieces--whichever piece makes the capture, it interferes with the other. Essentially a Grimshaw
  Grimshaw
  -Art:*John Atkinson Grimshaw, Victorian-era painter*Nicholas Grimshaw, English architect*Grimshaw Architects, British Architecture firm-Chess:*Walter Grimshaw, 19th century composer of chess problems...
  
  brought about by a white sacrifice on the critical square.

P

• Phase
  Phase of play
  Phases of play are parts of a chess problem which happen, as it were, concurrently rather than consecutively.Each problem has at least one phase: the post-key play or actual play; that is, the play after the key...
  
  - play after the key, after tries and set play each constitutes a phase of play. A problem with set play is said to have two phases (the set play being one phase, the post-key play being another); a problem with three tries would be a four phase problem (each try being one phase, with the post-key play the fourth). Play in different phases will sometimes relate to each other.
• Pickaninny
  Pickaninny
  Pickaninny is a term in English which refers to children of black descent or a racial caricature thereof. It is a pidgin word form, which may be derived from the Portuguese pequenino . In the Creole English of Surinam the word for a child is pikin ningre...
  
  - a problem in which, at some point in the solution, a black pawn on its starting square makes each of its four possible moves (forward one square, forward two squares, capture to the left and capture to the right). If the same behaviour is exhibited by a white pawn, it is an albino
  Albino (chess)
  An Albino is a chess problem in which, at some stage in the solution, a White pawn standing on its starting square makes each of its four possible moves: one square forward, two squares forward, capture to the left, and capture to the right...
  
  . (The term, which derives from an archaic reference to small black children, has a potentially derogatory meaning in modern English
  English language
  English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
  
  .)
• Plachutta
  Plachutta
  The Plachutta is a device found in chess problems: a white piece sacrifices itself on a square where it could be captured by one of two similarly-moving black pieces moving along a different line; whichever black piece captures, it interferes with the other...
  
  - a sacrificed white piece can be taken by two similarly-moving black pieces--whichever piece makes the capture, it interferes with the other. Essentially a pair of Holzhausen
  Holzhausen
  Holzhausen may refer to:Places*in Germany:**Holzhausen, Saxony-Anhalt, a municipality in the district of Stendal, Saxony-Anhalt**Holzhausen an der Haide, a municipality in the Rhein-Lahn district, Rhineland-Palatinate...
  
  interferences (or a Wurzburg-Plachutta interference) brought about by a white sacrifice on the critical square.
• Post-key play - the play following the key, that is, the lines of play which fulfill the stipulation of the problem. This is opposed to set play and virtual play (both of which may also be important elements in the attractiveness of a problem).
• Proof game - a type of problem in which the job of the solver is to construct a game of a given number of moves in which the final position is the one given by the composer. A kind of retrograde analysis.
• Pure mate
  Pure mate
  A pure mate is a checkmating position in chess in which the mated king and all vacant squares in its field are attacked only once, and squares in the king's field occupied by friendly units are not also attacked by the mating side .Such a mate occurred in the...
  
  - a mating position in which the mated king and all vacant squares in its field are attacked only once, and squares in the king's field occupied by friendly units are not also attacked by the mating side (unless such a unit is necessarily pinned to the king to avoid it interposing to block the check).

R

• Reflexmate - a selfmate in which both sides must deliver checkmate if they are able to do when it is their move. A problem where this stipulation applies only to black is a semi-reflexmate.
• Retrograde analysis
  Retrograde analysis
  In chess, retrograde analysis is a computational method used to solve game positions for optimal play by working backward from known outcomes , such as the construction of endgame tablebases. In game theory at large, this method is called backward induction...
  
  , retroanalysis - deduction of the move or moves leading up to a given position. A problem may be completely made up of retrograde analysis (as in a proof game, or a problem in which the task is to determine black's last move, for example), or it may be a part of some larger problem (for example, it may be necessary to determine that black has moved his king leading up to a given position, meaning he is unable to castle, and thus rendering correct a solution which would be otherwise incorrect).
• Round trip - a piece leaves a square, and then later in the solution returns to it by a circuitous route (for example, a rook moves e3-g3-g5-e5-e3). Compare with switchback, in which the route taken to the original square is direct.

S

• S - in algebraic chess notation
  Algebraic chess notation
  Algebraic notation is a method for recording and describing the moves in a game of chess. It is now standard among all chess organizations and most books, magazines, and newspapers...
  
  , the letter N is usually used to indicate the knight. In chess problems, however, the letter S (standing for Springer, the German name for the knight) is often used instead, with N instead being reserved for the popular fairy piece, the nightrider.
• Selfmate
  Selfmate
  A selfmate is a chess problem in which white, moving first, must force black to deliver checkmate within a specified number of moves against his will. Selfmates were once known as sui-mates.The problem to the right is a relatively simple example...
  
  - a type of problem where white forces black to mate him against black's will within a specified number of moves.
• Seriesmover
  Seriesmover
  A seriesmover is a chess problem in which one side makes a series of legal moves without reply at the end of which the other side makes a single move, giving checkmate or yielding stalemate, depending on the precise stipulation. Checks cannot be given except on the last move of the series...
  
  - a problem in which one side makes a series of moves without reply.
• Set play - play which is possible from the initial position of a problem if the other player moves first. For example, in a directmate, set play consists of lines of play starting with a black move (rather than a white move). When set play exists, the key move may be something which does not change the set play lines, in which case the problem is a complete block, or the lines in the set play may change, in which case the problem is a mutate. Set play is one phase of play.
• Solus rex (or Rex solus) - When either color (though usually black) has only their King piece left. The term is derived from Latin and literally means "lone king."
• Switchback - a piece leaves a square, and then later in the solution returns to it by the same route (for example, a rook moves e3-e5-e3). Compare with round trip, in which the route taken back to the original square is circuitous.

T

• Task - a highly unusual or bizarre theme, e.g. Babson-task or Valladao-task.
• Theme - the underlying idea of a problem, which gives it logic, coherence and beauty.
• Threat - a move or variation which white will play (usually following his key) if black does nothing to defend against it. Problems which do not have threats following the key are blocks.
• Three-mover - a problem with the stipulation "white to move and checkmate black in no more than three moves against any defence". In composition tourneys, there are often separate classes for three-movers, two-movers and more-movers (as well as classes for helpmates, selfmates and others).
• Try - a move which almost solves a problem, but is defeated by a single black defence, as opposed to the key (which actually does solve the problem). Variations after tries are called virtual play and may be an important part of what makes some problems pleasing.
• Turton doubling
  Turton doubling
  Turton doubling is a manoeuvre in chess in which a piece moves along a line , then a similarly-moving piece moves onto the same line in front of it, then this second piece moves again along this line, in the opposite direction to that of the first...
  
  - a kind of doubling in which one piece moves along a line allowing a second to move onto the same line in front of it; this second piece then moves in the opposite direction to the first. Named after Henry Turton. Compare with Zepler doubling.
• Twin - two or more problems which are slight variations on each other, composed by the same person. The variation is usually brought about by adding, removing or moving a piece in the initial setup.
• Two-mover - a problem with the stipulation "white to move and checkmate black in two moves against any defence". In composition tourneys, there are often separate classes for two-movers, three-movers and more-movers (as well as classes for helpmates, selfmates and others).

V

• Version - said of a problem which is an adaptation of an earlier one (it may have been altered to improve its economy or to eliminate a cook).
• Virtual play - the play following a try, as opposed to set play and post-key play.

W

• Wurzburg-Plachutta - mutual interference between two like-moving black pieces on different lines; essentially a pair of Holzhausen interferences where piece A interferes with pieces B in one variation, and piece B interferes with piece A in another. If the interference is brought about by a white sacrifice on the critical square, it is a Plachutta.

Z

• Zepler doubling
  Zepler doubling
  Zepler doubling is a manoeuvre in chess in which a piece moves along a certain line , then another friendly piece moves onto that same line, then the first piece moves again in the same direction as before...
  
  - a kind of doubling in which one piece moves along a line allowing a second to move onto the same line behind it; the first piece then moves again in the same direction as before. Named after Erich Zepler
  Erich Zepler
  Erich Ernest Zepler , later known as Eric, was a German-born electronics expert and chess problem composer....
  
  . Compare with Turton doubling.

External links

• Problemesis - contains a glossary and list of themes