A Guide to Variant Chess: Chess Problem Terms

Actual play The key move and the moves following it in a chess problem. èsolution

after key ètwinning

Albino White pawn field task shown in a problem.

Allumwandlung [German] Problem theme showing "all the promotions", that is, in orthodox chess, pawn to queen, rook, bishop and knight.

ally Piece of the same colour, or neutral. Plural = allies.

antipin A piece may not move to a cell because it will cause check (e.g. by acting as a hurdle for a hopper).

a posteriori [Latin] Describes a problem in which assumptions made about earlier play are held to be justified by the subsequent play that is made possible.

arrival Appearance of a piece on a cell. ~departure

assize One of a set of alternative formulations of the laws of a game, which the players may choose before starting.

Asymmetry Problem theme in which the arrangement of the pieces is symmetric, yet the play is paradoxically asymmetric.

auto- Prefix signifying same colour (e.g. auto-hopper hops only over allies). ~oppo-

bare king A position in which one player's forces are reduced to king alone. Considered a win for the other player in some games provided the next move does not result in two bare kings. èVCG: shatranj

Battle royal A gladiatorial combat involving only two royal pieces, one of each colour.
      Any royal {r,s}-leaper can helpstalemate another. When the two opposing pieces are of different types it is possible for one to attack the other without being attacked back, and in some cases a checkmate finale is possible.

black to move A stipulation sometimes used in endgame studies. e.g. Black to move, White wins.

brunner mate A type of fairy mate, involving the checkmated king being in multiple check with no orthodox last move. èVCG: Brunner chess. Two-move chess, Shinkman type.

Caissa The muse of chess. [W. Jones 1763]

castle (verb) To make the special compound move of king and rook.

chain A sequence of pieces each guarding its successor. Pawn chains often occur in play.

check Threat of immediate capture, particularly of a royal piece.
      Sometimes the player himself is said to be in check, since his choice of moves is restricted to those, if any, that annul the check. Check is not merely attack on the royalty by a particular piece, but the situation of its being under attack; it may be possible to prevent check by one piece only to open up check by another piece.
      In the FIDE Laws we are told that “the king moves to an adjacent square that is not attacked by an opponent's piece”. It should be added that this attack must be assessed AFTER the king move, not before. Otherwise a king attacked by a line piece (B, R, Q) could move a step away from it, since the square moved to is, at that time, unguarded. On the other hand, if we replace the line-piece by a grasshopper, it would attack the square behind the king and prevent it moving there!

checklock Special case of checkmate in which the player to move has physically no move.

checkmate Check that cannot be countered. The concept of checkmate is clearly related to the capture of the king, but we cannot substitute the rule that capture of the king is the aim of the game since then stalemate would be a win also.
      Either out of respect for the monarch, or because the coup de gras is clear on the preceding turn of play, the custom has arisen in orthodox chess that the capture of the king, which would follow if play were allowed to continue, is never actually carried out. However, in some variants, because of the convoluted nature of the play, it may be necessary to carry out the capture just to show that the king is indeed in check.

CHECKMATE IN 0 A trick question, usually solved by rotating the board, or correcting an illegality.

CHECKMATE IN N It is white's turn to move and you are required to find the unique first move that will enable white to checkmate black, against any moves black may choose to play, in not more than N moves; at least one line of play taking exactly N moves.

CHECKMATE ON GIVEN SQUARES Example:

citadel A special cell where a hunted king may seek refuge and thus save (draw) the game. These occur, usually accessible from corner cells, in a number of mediaeval variants. èVCG: Timur's game

colour Each side is assigned a colour, and may only move pieces of that colour. By current custom the colours are assigned according to the order of play, first player taking the lighter coloured pieces. The colours, and their players, are conventionally known as White and Black, regardless of the actual colours of the pieces, which may for example be yellow and brown. In variants for more than two players however there is no standard set of colours and they can be assigned arbitrarily. An alternative convention is used in Shogi where the pieces instead of being coloured are shaped tiles placed to face away from their player, this is so that captured men can be turned round to become part of one's own forces. Some games include pieces of an extra colour (or half black and half white) which are moved by either player. There may also be pieces moved by neither player; their moves being determined as a consequence of moves of the other pieces. èVCG: All-in chess; AKM: football, imitator, neutrals, supernumeraries.

combination A coordinated sequence of moves with two or more pieces of the same colour to gain some advantage. ~manoeuvre

compound move An alteration of the position in one turn of play that affects more than one piece. The compound moves in orthodox chess are castling, capture and promotion.

control A piece controls any cell on which it could capture, or where a royal piece would be in check. ~attack, guard, observe

coordinates To record the moves in a game, the files are lettered a, b, c, ... and the ranks are numbered 1, 2, 3, ... so that each cell, being at the intersection of file and rank, has a unique name consisting of a file-letter followed by a rank-number.
      For rectangular boards every combination of letter and number will represent a cell, but for boards of other shapes some will correspond to voids. To develop a mathematical theory of moves it is better to use numbers for both coordinates. èKTN: Theory of Moves

cordon A barrier of controlled or blocked cells that cuts off a king from part of the board.

countercheck A check in reply to a check. It is either a crosscheck or a return capture check.

countermate èVCG: Checkless chess.

crosscheck A countercheck by interposition.

deadlock Special case of stalemate in which all moves are physically blocked.

defence A move that stops a check or threat, or a system of moves designed to stop a more elaborate attack.

degeneracy The endgame situation when the Ks are accompanied by remnants of their forces insufficient for checkmate to be possible. No move by either player can win or lose.
      In orthodox chess the degenarate cases are: K v K; K,N v K; K,B v K; K,B v K,B. Also in these B may be replaced by any number of Bs all on the same colour cells.
      If we increase the forces slightly further we get to situations where checkmate is possible but cannot be forced. It can only happen if the adversary assists in his own downfall (i.e. in help-play).
      The cases are: K,N,N v K; K,N v K,N; K,N v K,B; K,B v K,B (White and Black Bs on opposite colour cells).

departure Disappearance of a piece from a cell. ~arrival

direct check The moved piece itself attacks the king.

direct play The normal adversarial play found in games, in which each tries to prevent the other from winning, as contrasted with ~help play or ~series play.

discovered check A piece other than the moved piece checks the king because its line of action, previously blocked by the moved piece, has been opened. Example:

double check Two pieces attack the king simultaneously. This can be the aim of a problem play.

double checkmate An unusual situation in which a checkmated player, ignoring the check to his king, can play a move to checkmate his opponent.

double stalemate Stalemate in which the stalemating player would also be stalemated if it were his turn to play.

DRAW An endgame problem stipulation; it is assumed that it is white's turn to play.

Duplex A problem in which there is a second solution in which the roles of black and white are reversed. For example in a duplex helpmate in 2, there is the usual solution in which black moves first and is mated on white's second move, but there is also a solution in which white moves first and is mated on black's second move.

Excelsior Problem showing a pawn travelling from its initial position to promotion.

fairy mate A final position using only orthodox pieces that is not mate under orthodox rules, but is under the variant rules in operation.

Fifty move rule A player must agree to a draw if requested by the other player when at least 50 consecutive move-pairs have been played without a reversible move (i.e. a capture or pawn move) being made. Originally introduced by FIDE in the 1920s. The rule was recently increased to 75 for certain special positions that have been shown by computerised endgame analysis to be winnable only in more than 50 pairs of irreversible moves against best defence. èLogjam, VCG: Knighted chess in disguise

fork Direct attack on two major pieces simultaneously. èmultirex

Game score? A stipulation meaning: Reconstruct the game that led to this position.

go A transformation of position that can be accomplished by one player in one turn; it may consist of a series of moves. In some games the change of position in one go can be considerable. èplay, VCG: Progressive chess, Two-move chess

groupmate èmultirex

half-pin Two pieces of the same colour stand in the way of a line piece attacking their king; so that when one moves the other is pinned.

help play Play (found in problems) in which the players cooperate in the required task, though not to the extent of making illegal moves. The aim of the play can be checkmate, stalemate, double stalemate, check, capture, symmetry and so on.

HELPMATE IN N It is black's turn to move and you are required to find the unique sequence of alternating black and white moves that will lead to checkmate of black on white's Nth move.

HELPMATE IN N½ It is white's turn to move and you are required to find the unique sequence of alternating white and black moves that will lead to checkmate of black on white's (N+1)th move.

HELPSTALEMATE Play as for helpmate but with stalemate the objective.

HELPCOMPELMATE Help-play leading to a self-mate in 1 position.

horizontal cylinder Board in which the top and bottom edges are joined. ètorus, VCG: Anti-chess, Horizontal cylinder chess

ideal mate A final position in which there is total economy and purity in use of the forces; every piece being involved and essential to the mate and no duplication of effort.

irreversibility of previous move This is a law not needed in orthodox chess, since none of the moves made by one player can be immediately reversed by the opponent, but it is essential in numerous variants; èVCG: All-in chess, Dynamo chess

italian mate èVCG: Progressive chess, Italian rules

LIKE-MAN-MOVER Restriction in which a player must move the same species of man as that last moved by the opponent.

lock A special case of mate in which the player to move has physically no available move, i.e. no considerations of check are involved. èchecklock, deadlock

logjam A set of pieces confined within a barrier with only one vacant cell, so that a convoluted series of movements is necessary to get one out (usually a king). Logjams may be puzzles in themselves or part of a larger problem, especially a retro. èFifty move rule

loose pin A pin in which the pinned piece can move along the pin line.

manoeuvre A sequence of non-capture moves by one or more pieces.

mate A state of the game in chess at which there is no legal move for the player whose turn it is to move. There can be no more play, so the game is at an end. If the player to move is in check the position is checkmate, while if he is not in check it is stalemate. Unfortunately this meaning of ‘mate’ is subverted by its habitual use as an abbrebviation of "checkmate". The term is also used as a verb meaning to make a move, or initiate a combination, ending in mate.

MAXIMUMMER Problem condition in which a player must play his longest move, or one of them if there is a choice. The length being calculated from cell centre to cell centre along the line of move. (The line of move need not be straight. èAKM: nonlinear pieces, mao, rose

MAXI-SELFMATE = Maximummer selfmate.

MINIMUMMER Like maximummer but the restriction is to shortest moves.

mirror mate A checkmate finale in which all squares of the king's field are vacant. This can be the aim of the stipulation.

mobility The average number of cells that can be reached by a piece under favourable circumstances. The mobility of a composite piece is the sum of the mobilities of its components provided their powers do not overlap. èAKM: For list of pieces and their mobilities on the 8 by 8 board

model mate A pure mate in which all the attacking officers, but not necessarily all the pawns, take part. This can be the aim of the stipulation.

monomate èmultirex

move The transfer of a single piece from one cell to another, together with any consequent alterations to the position.
      A move may be simple or compound; a compound move consists of an action (the simple move carried out by the player) and a reaction (a further move or moves specified by the laws of the game). In orthodox chess, capture, castling and promotion are compound moves.
      In some variants chain reactions may be possible where the consequent move has further consequences.

Multiplet Three or more closely related positions with the same stipulation. ètwin

Multirex The possibility of having more than one royal piece on each side has been experimented with from time to time and is known as multirex or rex multiplex. The results of such a variation in the rules lead to considerable complexities, because all the basic concepts, like check and mate, have to be redefined and there are several different ways this can be done, none of which has a clear claim to be the best way.
      The simplest way of generalising the rules, to my way of thinking, is to interpret a ‘check’ to a royal piece as a check to its player. Thus checkmate occurs if a royal piece is in check and all moves leave at least one of the royal pieces in still check, though not necessarly the same one. This type of checkmate I call groupmate. When there are two kings on one side, under these rules, they are often called siamese kings. It is often sufficient to fork or skewer two of the kings to give mate, there being no need in this case to guard flight squares, since flight of one of the kings leaves the other in check. èVCG: Twin-king chess
      The most often used form of mate, in terms of number of compositions published, is supermate, in which all the royalties have to be checked simultaneously. Moves that check one or some of the kings, but not all, may in this type of play have to be declared illegal or, if the checks cannot be answered, draws on the grounds of being, like stalemate, incomplete attempts to give checkmate.
      Another type of checkmate is monomate in which the aim is to checkmate one of the royalties, disregarding the others. Here again there is some variation among composers as to whether other kings can be checked at the same time that the one is mated, or whether one king can save another from mate by interposing itself.
      In T. R. Dawson's Problem Collection (currently with C. J. Feather I believe) multirex problems are classified not under ‘Force’ but under ‘Retroanalysis: illegal positions with excess force’!

Multi-stipulation A problem that is to be solved under two or more different stipulations.

NON-PASSANT RULE The rule that royal pieces may not pass through check. This applies to the king's double step in castling in orthodox chess. But in the case of royal riders it is usually assumed that they can ride through check unless the non-passant rule is specified (on the principle that anything not prohibited is allowed).

Palamedes Ancient Greek Prince to whom is attributed numerous inventions including the game ›Petteia, thought by some to be a precursor of chess. Hence the adoption of the name Palamède for the first chess magazine (founded by L.C.M. de la Bourdonnais in 1836) and as a pen name by several chess writers.

passing check A check that occurs during a move but is not evident at the beginning or end. Passing checks can occur when (1) a royal piece passes over a guarded square or (2) a piece passes through a square on which, if it stopped, it would itself check, or cause another piece to check, the opposing royalty, or (3) a pinned piece or shielding piece moves from one pinned or shielding position to another.
      Passing checks of type (1) are specifically barred in orthodox chess by the part of the castling rule that states that kings may not castle through check. However in games or problems with royal riders, they are often allowed to ride through check. Where this type of passing check is prohibited the non-passant rule should be explicitly stated.
      Passing checks of type (2) are allowed freely in orthodox chess (though this is not explicitly stated in the FIDE laws), so it is usual to assume that passing checks of all types are allowed unless specifically barred.
      Passing checks of type (3) can occur for example in cylinder chess or with curved-path pieces such as roses.

perpetual check A special case of draw by repetition, in which one player can give check on every succeeding move.

pin A position in which a certain piece if removed would leave its king in check. The piece is said to be pinned. ~antipin
      One of the laws of orthodox chess says that a pinned man can still check, since its move to capture the oposing king would end the game, so its exposure of its own king to check would not matter in this case. Alternative interpretations of this rule have led to several interesting variants. èVCG: Brunner chess, Pin chess

pin mate Checkmate with a defender unable to defeat the check because pinned.

play A move or series of moves that can be made in one turn.

pure mate A checkmate or stalemate in which the cells of the king's field are blocked or attacked no more than once. Pure mate may be the aim of the stipulation.

recursion There are sometimes dangers in formulating rules that have to be repeatedly applied in order to determine the legality of a move or situation. These can sometimes lead to endless arguments or infinite regressions that never settle the question. A supplementary rule may be necessary to settle these cases. èVCG: Symbolic chess, Barrier chess, Checkless chess, Checkless circe chess, Pin chess

REFLEXMATE IN N Selfmate played under the rules of reflex chess: white plays first and forces black to deliver checkmate on his Nth move, assisted and obstructed by the rule that either player must give checkmate in one if the chance arises.

resignation Conceding defeat; which a player may do at any stage before a terminal position is reached. To cover the case when a player simply walks out, or fails to post a reply, a time limit needs to be specified after which he cannnot return to resume the game. Moving the king into check is regarded as signalling resignation.

Retroanalysis The art of deduction from a chess problem position, and any other information given, of possible plays that may have led up to the position, on the assumption that it has been reached from the usual opening position by legal though not necessarily sensible play.

rex exclusive (RE) Means the variant rules do not apply to the kings (or any other royal pieces).

rex inclusive (RI) Means the variant rules apply to the kings (or any other royal pieces).

rex multiplex èmultirex

royal battery One with royalty as front piece.

selfcheck An illegal move that leaves your own king in check.

SELFMATE IN N White plays and forces black to deliver checkmate on his Nth move.

self-pin A move that leaves the moved piece or an allied piece pinned.

SEMI-REFLEXMATE IN N Reflexmate with the reflex condition applying only to black.

Series play Play in which one player makes two or more moves while the other player does nothing. The usual convention is that check may only be given on the last move of the series, and the player may only be in check at the start of the series. èVCG: Progressive chess, Two-move chess, Triplets
SERIESMATE IN N White is to play and checkmate black in N moves, black not moving at all.
SERIESTALEMATE Similar to seriesmate but with stalemate as the aim.
SERIESHELPMATE IN N Black is to play a series of N moves to reach a position where white can give checkmate in one move.
SERIESHELPSTALEMATE Similar to serieshelpmate but with stalemate as the aim.

Set play In a chess problem, the moves that follow if it is assumed to be the other player's turn to play.

Siamese kings èmultirex

skewer Pin of one major piece against another. èmultirex

solution All the interesting play to be found in a chess problem. This usually! includes the actual play, but may also involve set play, try play, retroanalysis, and perhaps other features.

stalemate The player to move has no legal move and is not in check. This may be because the moves are physically blocked, or because they would expose a royal piece to check. èdeadlock

stalematemate A checkmate position in which the mating player is ‘stalemated’ if capture of the king is considered illegal.

step A straight move {r,s} which does not pass over the centre of any intermediate cell. This occurs when the coordinates r and s have no common divisor other than 1; the shortest steps are: {0,1}, {1,1}, {1,2}, {1,3}, {2,3}, {1,4}, {3,4}, and so on.

strict The exact number of moves must be played, not less than the specified the number.

"SUIMATE" An old name for selfmate.

supermate èmultirex

torus Board (used in problems) in which left and right edges are joined and also top and bottom edges = combined vertical and horizontal cylinder.

"Total" Sometimes used to mean èRex Inclusive, i.e. the new rules apply to all the pieces.

try A move that almost solves a chess problem. In the case of a direct move problem there is ideally only one move that defeats the try.
Try play A try or tries and the moves following.

unit A unit of time is a move, of space a cell, of force a piece, of law a rule.

unpin Release of a pin; this may be by the pinning piece moving away (withdrawal unpin), by a piece interposing on the pin line (interference unpin) or by capture of the pinning piece (capture unpin).

variation A branch-line of play, in problem or game analysis, following an initial move or introductory play; usually classified as main and side variations.

win According to the current laws of Chess checkmate is counted a win for the player who makes the last move, while stalemate is a draw.
WIN A stipulation for endgame study problems.

zeroposition A problem position which is not itself the starting position for play, but generates two or more such starting positions by a twinning procedure, such as moving a piece. The following example seems to have been the first of the kind.

zugzwang The obligation to move.