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Glossary of Problem Terms by Peter Wong

Highlighted words in brown have their own entries in this glossary.
| A | B | C | D | E | F | G | H | I | K | M | N | O | P | R | S | T | V | WZ |
 
Actual play In directmates, the variations that occur after White has made the key. In helpmates, the move sequence of the normal solution, as opposed to any set play.
Albino A theme in which a white pawn, on its starting rank, makes each of its four possible moves in turn – two forward steps and two captures – during the course of the solution.
Allumwandlung A German term (often abbreviated to AUW) for a theme in which the four possible types of promotion – to queen, rook, bishop, and knight – all take place during the course of the solution.
Battery An arrangement of two pieces capable of giving a discovered attack. A direct battery is aimed at the opposing king, whereas an indirect battery is aimed at the king’s adjacent squares.
Block position A position after White has played a key that makes no threat but puts Black in zugzwang, i.e. a situation in which every possible move by Black entails a weakness that enables White to force mate.
Bristol A theme consisting of the following line-clearance manoeuvre. A long-range piece moves along a line, crossing over a critical square, to enable another long-range piece of the same colour to access that square by following on the same line.
By-play Secondary variations that are not part of a problem’s thematic play.
Changed play Variations that are altered in some way from one phase to another, e.g. a mating move that occurs in the set play is replaced by another mate in the actual play, against the same defence.
Composition A chess composition is synonymous with a chess problem.
Cook An alternative solution, not intended by the composer, that renders a problem unsound.
Cross-check A tactic in which White answers a check by interposition, and gives check as well with the same move.
Defence In directmates, a black move that parries White’s threat, or any black move in a block position.
Directmate A type of problem in which White moves first and forces mate in a specified number of moves, against any defence by Black.
Dombrovskis A directmate theme in which certain moves recur in the try play and actual play, but with their functions changed in a paradoxical way. In a two-mover, the solution follows this pattern: a white try threatens the mate 2.A, and is refuted by the black defence 1…x!; but after the key, it is this defence 1…x that enables White to mate with 2.A.
Dual A choice of equally playable white moves (mates or continuations) in a directmate variation. Such non-unique white play is normally regarded as a flaw, especially in a thematic variation.
Duplex A solving condition that requires the problem’s task to be fulfilled twice: once normally, and once again with White and Black exchanging their roles.
Echo A theme in which a mating configuration recurs on different parts of the board in separate variations.
Excelsior A pawn begins on its initial rank in the diagram, and proceeds to promote during the course of the solution.
Fairy chess The field of unorthodox problems that involves some kind of modification of the standard chess rules. Fairy problems may employ one or more of the following: (1) an unconventional task to be achieved (e.g. series-movers), (2) an overriding rule or condition that applies to the play (e.g. all captures are deemed illegal), and (3) special pieces that move differently from those of the regular set (e.g. the nightrider).
Flight A square that is accessible to the black king.
Focal play A theme in which a black line-piece (queen, rook, or bishop) “focuses” on two squares in different directions, and upon moving, is forced to “lose the focus” and unguard one of the squares.
Grimshaw A theme in which two pieces of the same colour (usually a rook and a bishop) interfere with each other’s line of action, by playing in turn to a square where the two lines intersect.
Half-battery An arrangement in which two pieces of the same colour stand between a friendly line-piece and the enemy king, so that moving either of the intermediate pieces off the line would produce a battery with the remaining piece.
Half-pin A theme in which two black pieces stand on a line between the black king and a white line-piece, such that moving either black piece off the line leaves the remaining piece fully pinned. This pin is then exploited by White who gives a pin-mate.
Helpmate A type of problem in which the two players cooperate to enable White to mate Black, in the specified number of moves. Black usually plays first, e.g. the solution of a ‘Helpmate in 2’ consists of the sequence, 1.Black begins, White moves, 2.Black moves, White mates.
Ideal mate A pure mate in which every piece on the board participates.
Key The unique first move by White that solves a directmate problem. In notation, a key is signified by ‘!’.
Knight-tour A theme in which a white knight makes the maximum number of eight possible moves in turn, such as by delivering eight battery mates individually against different black defences.
Knight-wheel A theme in which a black knight produces the maximum number of eight variations, by making all of its eight possible moves in turn and inducing a different white response in each case.
Mate in ‘n’ A stipulation indicating the problem is a directmate, in which White has to force mate in ‘n’ moves.
Mate transference A type of changed play seen in directmates, where the same white mating move occurs over two phases of play, but is induced by different black moves. A white mate is thus ‘transferred’ from one black defence to another.
Meredith A problem that consists of eight to twelve pieces.
Miniature A problem that consists of no more than seven pieces.
Model mate A pure mate in which every white piece participates, with the possible exception of White’s king and pawns.
More-mover A directmate problem in which White has to mate in four moves or more.
Mutate A form of directmate in which White has set replies provided for all of Black’s moves in the initial position, but a waiting key changes the white response to at least one of these black moves.
Novotny A theme in which White plays a piece to a square that intersects two black defensive lines, usually controlled by a rook and a bishop, so that when either captures the white piece, the other black piece’s line will remain closed.
Orthogonal-diagonal transformation A theme framework mostly seen in helpmates, in which the strategic effects that take place on orthogonal lines in one phase are shown again in another, but changed to occur on diagonal lines, and vice versa.
Phase A distinct part of a problem’s full solution, consisting of a group of variations, such as actual play, set play, or try play. Several phases of actual play may occur in problems that involve twins or multiple solutions.
Pin-mate A mate that is dependent on the pin of a defending piece in order to be effective.
Problem A composed position with a task that has to be accomplished, such as how to achieve mate in a specified number of moves.
Progressive twin A type of twinning for creating additional solving positions. Each adjustment specified to produce position (b), (c), etc. is applied to the starting position of the previous part (rather than the initial diagram, as in normal twinning). Thus, to set up position (b), make the specified change to the diagram as usual, but to set up part (c), start from position (b) and make the further specified change, and so on.
Pure mate A mating position in which every square next to the black king is covered only once, i.e. each square is uniquely guarded by one white piece or blocked by a black one.
Refutation The unique black move that defeats a white try in a directmate problem. In notation, a refutation is signified by ‘!’.
Rundlauf A roundabout trip made by a piece that finishes on its original square.
Self-block A type of error Black commits by placing a piece next to the black king, preventing the king's escape to the occupied square.
Selfmate A type of problem in which White plays first and forces Black to give mate in the specified number of moves, while Black does not cooperate and tries to avoid mating White.
Series-helpmate A type of series-mover in which Black plays a number of consecutive moves and aims for a position where White can deliver mate (or stalemate, in a series-helpstalemate).
Series-mate A type of series-mover in which White plays a number of consecutive moves and aims to mate Black (or stalemate Black, in a series-stalemate).
Series-mover A category of unorthodox problem types in which one player makes a sequence of consecutive moves while the other side remains stationary. The aim of the move sequence varies according to the type. In all cases the player of the series is not allowed to move into check, or to give to check except (optionally) on the last move.
Series-selfmate A type of series-mover in which White plays a number of consecutive moves and aims for a position where Black is forced to deliver mate (or stalemate, in a series-selfstalemate).
Set play The play that would occur if the side that normally moves first could miss a turn. In directmates, set play refers to any variations that are already prepared in the initial diagram, before White makes the key. In helpmates, set play means an additional move sequence that solves the problem, but which is commenced by the player (usually White) who moves second in the actual play.
Shortest proof game A type of problem in which the task is to reconstruct a legal game that leads to the diagram position. The shortest possible game is required, and its length is given in pairs of single moves, e.g. “SPG in 10” indicates the position is attained after Black’s 10th move.
Square-obstruction A strategic effect in which a piece arrives on a square, and thereby prevents a friendly piece from occupying it.
Square-vacation A strategic effect in which a piece departs from a square, and thereby enables a friendly piece to occupy it.
Stipulation The task to be achieved, and any additional condition, that accompany a problem position, e.g. “Mate in 2”.
Tempo play A kind of waiting manoeuvre executed by a player who is already positioned correctly, serving no function other than to use up the extra time available.
Theme The principal idea or effect shown in a problem.
Threat Potential play by White that would be effective if Black makes an indifferent move.
Three-mover A directmate problem in which White has to mate in three moves.
Try A first move by White that nearly solves a directmate problem, but is defeated by only one black defence, called the refutation. In notation, a try is signified by ‘?’.
Try play The variations of a directmate that occur after White has played a try.
Twin Multiple settings of a problem that differ from one another slightly in their positions, but each requiring its own solution. The diagram position is regarded as part (a); additional positions for solving, parts (b), (c), etc., are formed by adjusting the diagram in the way specified in the stipulation.
Two-mover A directmate problem in which White has to mate in two moves.
Variation A line of play in a directmate problem, starting with a black move or defence and ending with a white mate.
Virtual play See Try play.
Waiting move A type of key by White that makes no threat but creates a block position where Black is in zugzwang, i.e. a situation in which every possible move by Black entails a weakness that enables White to force mate.
Zagoruiko A directmate theme that specifies a framework of changed variations. At least two black defences lead to changed white responses, with each defence provoking at least three different white replies in separate phases.
Zilahi A helpmate theme in which two white pieces exchange their functions of getting captured and giving mate in two phases of play.