Technology, online play, and variants

A program that analyzes a position, compares legal move sequences, and recommends options based on its calculations.

A visual application that lets users control chess software through a board, controls, and panels instead of text commands.

A chess-analysis program that runs on the user's own device and uses that machine's processor and memory.

A chess-analysis program that performs its calculations on a remote computer and returns the results over a network.

The move sequence a chess-analysis program currently considers the best continuation for both sides from a position.

An indicator of how far a chess engine's current search has progressed from the position being analyzed.

A measure of how many positions a chess engine processes per second during search.

Memory that lets a chess engine reuse results for positions it has already searched.

A database of opening positions and moves that a chess program can consult before normal search.

A precomputed database that gives exact results for endgames within a limited number of pieces.

A neural-network architecture designed to evaluate chess positions while updating efficiently between nearby positions.

A method that skips branches unable to change the final choice when both sides seek their best result.

A representation with 64 zero-or-one indicators, one per square, marking which squares belong to a chosen set.

A precomputed endgame metric measuring the distance to a capture or promotion, or to mate if it comes first.

A metric counting the distance to forced mate when the winner hastens it and the defender delays it.

A precomputed endgame metric measuring the distance to mate or to the next move that resets the fifty-move counter.

A compact precomputed structure that stores minimal outcome information for many endgame positions.

A procedure that assigns a numerical estimate to a position so a chess program can guide its search.

An error caused when a decisive consequence lies just beyond the search limit and distorts the evaluation.

A strategy that repeats search with increasing limits so a completed result is always available.

A technique that initially searches moves placed late in a position's analysis order at reduced depth.

An algorithm that chooses a move while assuming both sides will always make their best available decisions.

A method that repeatedly explores variations and spends more analysis on moves that appear promising.

A technique that chooses which moves to search first so unhelpful branches can be rejected sooner.

An analysis mode that displays several candidate moves with a line and evaluation for each one.

A heuristic that tests a fictional pass to discard positions that appear clearly sufficient.

A test that counts every legal move sequence to an exact search depth.

A mode in which an engine searches while the opponent's clock runs, usually from a predicted reply.

An optimization that fully searches the first candidate and initially tests later moves with a narrower check.

An extension that continues selected tactical moves until the position is stable enough to evaluate.

A fast calculation that estimates the material balance of successive captures and recaptures on one square.

The exact win, draw, or loss outcome that a tablebase assigns to an endgame position.

A method that creates a quickly updatable numerical fingerprint for the complete state of a chess position.

An online chess feature that queues a move during the opponent's turn for automatic execution afterward.

Making the opponent run out of time, usually to win although some positions are drawn.

A Lichess Arena option that voluntarily cuts a player's time in exchange for an extra tournament point after a qualifying win.

An online-chess input error that causes a different legal move from the one the player intended to enter.

Deliberately playing below one's true strength to make a displayed rating or competitive level artificially low.

Artificially inflating an account's competitive rating or results through arranged outcomes or other non-competitive behavior.

Using an account that presents a strong player as far weaker than the player really is.

More than one person using the same chess account, especially when someone plays games on behalf of the account holder.

A setting that automatically turns a pawn reaching the last rank into a queen.

A preprogrammed reply that executes only when the opponent makes the exact predicted move.

An interruption of the link between a player's authorized device and the platform hosting the game.

Delay between a player's action and its arrival at the server or the return of the response.

A mechanism that partially adjusts the clock for network delay measured by the platform.

A setting that requires approval of a selected move before it is submitted to the online board.

The digital environment that hosts the board, clock, and controls needed to play an online chess game.

A feature that restores an earlier position by withdrawing a move that the game has already accepted.

Using a chess engine for evaluations, moves, or analysis during a game in which that help is prohibited.

Rules, controls, and investigative methods designed to prevent and detect prohibited assistance or competitive manipulation.

Intentional cooperation between participants to deceive others, obtain improper help, or manipulate a competition.

A regulatory presumption triggered when an approved statistical analysis exceeds the official threshold for a performance.

The deliberate use of prohibited help or competition manipulation to obtain an improper advantage.

An intentional and improper alteration of a competition's result or course in order to obtain an advantage.

Information or advice from outside the player's own thinking that is used during a game.

The principle of competing honestly, following the rules, and letting results depend on the players' genuine play.

A tool that examines games and competition data to identify integrity patterns that may warrant review.

Competitive participation under an identity that does not belong to the person actually playing or recorded as the player.

A tournament or game entered in competitive records as real even though it did not genuinely occur as represented.

An improper agreement or plan to predetermine the result of a game or competition.

A breach of an online event's technical or supervision requirements that can be penalized without itself implying cheating.

The deliberate distortion of results, identities, or records to create or exploit a rating that misrepresents genuine competition.

A cheating allegation made without acceptable grounds that could give a reasonable person a genuine suspicion.

The deliberate creation of a chess position or task designed to express an idea through a defined solution.

A deliberately constructed position that sets a precise task and has a solution intended by its composer.

A composition in which White must force a win or draw from a position created by the composer.

A problem in which White moves first and forces mate against every Black defense within the stated number of moves.

A directmate in which White must force checkmate in no more than two White moves.

A directmate in which White must force checkmate in no more than three White moves.

A directmate problem in which White must force mate in four or more White moves.

A problem in which Black and White cooperate so that White checkmates the black king in the stated number of moves.

A problem in which White forces a resisting Black to checkmate the white king.

Backward reasoning that deduces which earlier moves or events are compatible with the current position and legal chess play.

A legal sequence from the initial chess position to a given position, showing that the target position can be reached.

Chess composition that introduces pieces, conditions, boards, or other rules that differ from orthodox chess.

An unintended solution that begins with a different first move from the author's solution and makes the composition unsound.

Virtual play already prepared in the initial position before the actual first move of the solution.

A nearly correct first move that fails to exactly one Black defense, called the refutation.

The correct first move that begins the actual solution of a problem, especially a directmate.

A compositional checkmate combining purity around the mated king with economical participation by the mating side's pieces.

A composition theme where a White piece occupies the intersection of two Black defensive lines and forces interference between them.

A composition theme where two same-colored pieces mutually block one another by occupying the same intersection square in separate variations.

The situation in which an identical chess composition already has an earlier priority date.

A composition theme in which every Black promotion is answered by a White promotion to the same piece.

A composition in which White's first move creates no threat and every Black move permits a prepared White response.

A theme in which one piece moves ahead along a row, column, or diagonal so a same-color piece can follow on that line.

An added chess rule in which a captured piece is immediately reborn on a designated home square.

A situation in which more than one continuation satisfies the composition's task after the first move.

A theme in which several continuations appear possible, but after each defense exactly one works and the others are excluded.

A theme in which a pawn starts on its original row, crosses the board, and promotes, meaning it becomes another piece.

A nonstandard chess piece that hurdles another piece on a row, column, or diagonal and lands exactly one square beyond it.

A mechanism in which two Black pieces screen their king on one line and either one's departure prevents the other from moving away.

A theme in which the same Black defenses receive White mating replies that rotate cyclically between two or more parts of the solution.

An added rule that normally requires Black to choose a legal move with the greatest straight-line distance from start to finish.

A composition whose initial diagram contains eight to twelve units, counting every king, queen, rook, bishop, knight, and pawn.

A composition whose initial diagram contains at most seven units, counting kings, queens, rooks, bishops, knights, and pawns.

A nonstandard chess piece that repeats one or more knight steps in the same direction as a single move.

A convention that splits a solution into parts when permissions for certain special moves depend on incompatible legal histories.

A theme in which a sacrifice at two crossing defensive lines makes either capturing piece obstruct the other.

A problem in which White forces Black to mate White and either side must mate immediately whenever possible.

A family of problems in which one side makes several consecutive moves while the other side remains stationary.

The property that a chess composition has exactly its intended solution and no defect that invalidates it.

The exact task a chess composition requires, together with any conditions needed to interpret that task.

Thematic play contained in hypothetical possibilities of a composition even though it is not the line ultimately carried out.

A theme in which the same two or more Black defenses receive different White mates across at least three phases of a problem.

A chess variant with 960 legal back-rank starting arrangements and adapted castling rules.

A four-player team variant on two boards where captured pieces are passed to a partner and can be dropped back into play.

A two-player variant where captured pieces change sides, enter a reserve, and can later be dropped back onto the board.

A variant where every capture causes an explosion that removes the captured piece, the capturer, and nearby pieces under special rules.

A variant that keeps normal chess rules and adds an immediate win for delivering a third legal check to the opposing king.

A variant that keeps normal chess rules and lets a player win by legally moving their king onto one of the four central squares.

An asymmetric variant where one side controls a large pawn horde without a king while the other keeps a normal chess army.

A pawnless variant with a special starting position where the goal is to race your king to the eighth rank without giving check.

A reversed-objective variant where captures are compulsory and you normally win by losing all your pieces or having no legal move.

A chess format where an agreed starting advantage is used to compensate for a difference in playing strength.

A format in which an authorized player combines personal judgment with analysis software and searchable game collections during play.

A two-board variant in which every moving piece transfers to the opposite board after completing its move.

A 10-by-8 variant adding one piece that combines bishop and knight movement and another that combines rook and knight movement.

A hybrid sport in which two competitors alternate rounds of one continuing chess game and one continuing boxing bout.

A variant in which every turn combines a chess move with the mandatory placement of a shared blocking duck.

A hidden-information variant in which each player sees only their pieces and the squares those pieces can legally reach.

A family of variants in which four armies take turns in one game on a shared four-sided board.

Władysław Gliński's variant played on a three-colored hexagonal board containing 91 cells.

Christian Freeling's 10-by-10 variant with two pieces combining familiar movements and pawns that promote by restoring captured friendly pieces.

A hidden-information variant in which a referee validates attempted moves and communicates only limited facts.

A variant in which each normal turn gives the same player two consecutive moves.

A family of variants in which each turn contains one more move than the preceding turn.

A standard-board variant that adds a hawk and elephant from reserve when an original piece vacates its starting square.