Arimaa/Glossary

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Adjacent[edit | edit source]

The d4 square is adjacent to c4, e4, d3, and d5. In Arimaa, adjacent does not include diagonals, which have no place in the rules.

Arimaa Challenge[edit | edit source]

The Arimaa Challenge was an annual match between a top bot and top human players; humans dominated for eleven years, until a bot's surprise victory in 2015.

Away trap[edit | edit source]

An opponent's home trap: c6 and f6 are away traps for Gold, while c3 and f3 are away traps for Silver.

Basket[edit | edit source]

A basket is like a frame or fence, but does not directly involve a trap square. A piece in a basket is blocked on three sides, and can't escape on the fourth side.

Blockade[edit | edit source]

A blockaded or smothered piece is surrounded by pieces which it can't push away. A blockaded square is occupied by a piece which can't be pushed off. See also Phalanx, Frame, Immobilization.

Camel[edit | edit source]

The second strongest of the six unique Arimaa pieces. Each side has one camel.

Capture[edit | edit source]

A captured piece is removed from the board; a piece is captured when it occupies a trap square with no friendly piece beside it. There are two common ways a piece might be captured: it could be dislodged into an undefended trap, or might already be on a defended trap square which then becomes undefended.

Cat[edit | edit source]

The fifth strongest of the six unique Arimaa pieces. Each side has two cats.

Choke[edit | edit source]

A choked piece is blocked by its own rabbit. Unable to retreat homeward, advanced rabbits can sometimes be used against their owner.

Dislodge[edit | edit source]

To push or pull an opponent's piece. Dislodge should not be confused with capture.

Dog[edit | edit source]

The fourth strongest of the six unique Arimaa pieces. Each side has two dogs.

Draw[edit | edit source]

Prior to July 1, 2008, one who had lost all eight rabbits could still get a draw by capturing all remaining enemy rabbits. Draws are no longer possible, as a game now ends when one side is out of rabbits.

East wing[edit | edit source]

The right side of the board viewed from Gold's perspective, specifically the f-, g-, and h-files.

Elephant[edit | edit source]

The strongest of the six unique Arimaa pieces. Each side has one elephant, which is the only piece that cannot be pushed or pulled by the opponent.

Elephant deadlock[edit | edit source]

The two elephants are deadlocked when both remain next to the same trap, preventing any capture therein.

Elimination[edit | edit source]

A player wins by elimination if the opponent has no rabbits left. In the rare event that each player loses his last rabbit in the same move, the one who made the move wins. See also Goal, Immobilization.

Endgame[edit | edit source]

The game phase when a goal line can no longer be blocked reliably, and thus gameplay centers around goal threats. See also Opening, Middlegame.

Exchange[edit | edit source]

An exchange or trade occurs when each side captures material within a few turns. If each side captures a rabbit, that is a rabbit exchange. If the gold camel is captured and then a silver horse is captured, that is a camel-for-horse exchange. See also Sacrifice.

False protection[edit | edit source]

When two friendly pieces next to a trap could each be dislodged in two steps, resulting in a capture in an apparently protected trap. See also Mutual protection.

Fence[edit | edit source]

A fenced piece is stuck next to a trap, and could only step into that trap. A fence may result in a capture, frame, or hostage.

File[edit | edit source]

One of eight columns on an Arimaa board. From Gold's perspective, the a-file is on the left and the h-file is on the right. From Silver's perspective, it is the reverse.

Flip[edit | edit source]

In one turn, a piece might pull and then push a weaker enemy piece; the stronger piece finishes where it started, having flipped the enemy piece two squares. A piece surrounded on three sides cannot do a flip, as there is not room for the movement.

Fork[edit | edit source]

A forked piece is simultaneously threatened with capture in two different traps. The forked piece would have to be on c4, c5, d3, d6, e3, e6, f4, or f5.

Four-for-two[edit | edit source]

A four-step move which can be undone in two steps by the opponent. Like three-for-ones, four-for-twos usually give away time.

Frame[edit | edit source]

A piece which is on a trap square, securely surrounded on three sides by opposing pieces, has been framed. Its lone friendly defender is pinned. See also Basket, Phalanx, Blockade.

Freeze[edit | edit source]

A piece is frozen if no friendly piece occupies an adjacent square, and a stronger enemy piece does occupy one. A frozen piece cannot move until a friendly piece is beside it, or until the stronger enemy piece leaves. A frozen piece can still be pushed or pulled by the opponent.

Free piece[edit | edit source]

A free piece can move around with limited risk. Blockades, frames, hostages, trap attacks, and goal threats may restrict pieces on both sides, leaving other pieces to decide the game. Having the strongest free piece or strongest local piece can be a large advantage.

Friendly piece[edit | edit source]

For Gold, any gold piece is a friendly piece. For Silver, any silver piece is friendly. See also Freeze, Capture, Mutual protection.

Goal[edit | edit source]

If a rabbit reaches the opponent's home rank, the game is won by goal, which is the usual way a game ends. See also Elimination, Immobilization.

Goal attack[edit | edit source]

An ongoing goal threat. See also Trap attack.

Gold[edit | edit source]

Gold is the player with gold pieces. Gold is both the first to set up and the first to move. See also Silver.

Hang[edit | edit source]

A hanging piece is exposed to immediate or forced capture. See also False protection.

Home trap[edit | edit source]

A trap on a player's third rank. The squares c3 and f3 are Gold's home traps; the squares c6 and f6 are Silver's home traps. See also Away trap.

Horse[edit | edit source]

The third strongest of the six unique Arimaa pieces. Each side has two horses.

Hostage[edit | edit source]

A hostage piece is held near a trap and threatened with capture should a friendly defender leave.

Immobilization[edit | edit source]

A player wins by immobilization if the opponent has no piece which can move, or if any move the opponent could make would recreate a position they created twice before. See also Freeze, Blockade, Goal, Elimination.

Key square[edit | edit source]

A square north, south, east, or west of a trap square. See also Trap attack.

Lemming[edit | edit source]

Not recognizing a lost cause, some bots will go all out to save a doomed strong piece. The bot sends over a weak piece to defend it, only to have the weak piece captured with the strong piece no better off. The cycle may repeat several times, with the bot sending over lemmings and the opponent capturing them.

Linchpin[edit | edit source]

A stabilising piece in front of a non-elephant hostage-holder. For instance, if the gold camel holds a silver horse hostage on a3, Gold might have a linchpin horse on a4 to unfreeze the camel if it is pulled forward.

Middlegame[edit | edit source]

The period between the opening and endgame.

Mutual protection[edit | edit source]

When two or more friendly pieces protect each other from capture in a trap they are adjacent to. See also False protection.

Opening[edit | edit source]

The period from setup roughly until the first capture. See also Middlegame, Endgame.

Overload[edit | edit source]

Multiple threats might overload the enemy elephant, if no other piece can defend.

Phalanx[edit | edit source]

When every square a piece could be pushed onto is already occupied. A phalanx may be part of a larger blockade, or may simply block a particular move.

Pin[edit | edit source]

A lone friendly piece supporting a framed piece is said to be pinned. If a pinned piece moves, the framed piece disappears instantly.

Pinch[edit | edit source]

A capture defense in which an enemy piece is surrounded so that it cannot pull or flip a piece into a trap.

Postal game[edit | edit source]

A slow game in which the players are allowed a specified number of hours or days to complete each move. Also known as a correspondence game.

Pull[edit | edit source]

A piece can pull a weaker enemy piece by first stepping onto an unoccupied adjacent square, and then moving the enemy piece onto the square that was just vacated. A pull requires two steps.

Pull and replace[edit | edit source]

When a piece pulls a weaker enemy piece, and then a friendly piece steps onto the square the enemy piece was pulled from.

Push[edit | edit source]

A piece can push a weaker enemy piece by first moving it to an adjacent empty square, and then itself stepping onto the square which that enemy piece had occupied. A push requires two steps. A phalanx may block a push.

Push and replace[edit | edit source]

When one piece pushes another and steps away, allowing a different friendly piece to take a square formerly occupied by an enemy piece. See also Pull and replace.

Quadrant[edit | edit source]

A quarter of the board (16 squares), distinguished by compass directions from the perspective of Gold. The northwest quadrant contains the c6 trap, the northeast contains f6, the southwest contains c3, and the southeast contains f3.

Rabbit[edit | edit source]

The weakest unit on the board, and the only piece that cannot be moved backward by its owner. Each player starts with eight rabbits, and aims to eventually get one to goal.

Rank[edit | edit source]

One of eight rows on an Arimaa board. Gold begins the game with 16 pieces on the first and second ranks, while Silver begins with 16 pieces on the seventh and eighth ranks. The home rank for Gold is 1, while Silver's is 8.

Repetition rule[edit | edit source]

A player who has created the same position twice may never create that exact position again. This is a consideration in sequences where players undo each other's moves.

Rotation[edit | edit source]

When a piece holding a blockade or frame is replaced by a weaker piece or a phalanx, the original piece has rotated out. If a hostage defender is replaced, usually by multiple weaker pieces, the original defender has rotated out. A piece can likewise rotate out of a trap control fight. See also Swarm.

Sacrifice[edit | edit source]

A strong piece might be sacrificed so that a friendly rabbit can reach goal. A weak piece might be sacrificed while one secures a frame or hostage. Likewise, one might have to give up a piece to break an elephant blockade or stop an enemy goal.

Scatter[edit | edit source]

A player whose home trap is invaded may scatter his nearby pieces to avoid capture.

Setup[edit | edit source]

At the start of a game, Gold sets up his pieces on the first and second ranks, in any configuration he chooses. Silver then sets up her pieces on the seventh and eighth ranks.

Silver[edit | edit source]

Silver is the player with silver pieces. Silver is second to set up and second to move. See also Gold.

Step[edit | edit source]

A piece can step onto any unoccupied adjacent square. A player takes one to four steps on any turn. Any piece move requires one step; a push or pull uses two steps, since two different pieces move.

Strength[edit | edit source]

There are six unique types of pieces, each with a different strength. A piece can push, pull, or freeze any weaker enemy piece. From strongest to weakest, the units are elephant, camel, horse, dog, cat, and rabbit.

Strong piece[edit | edit source]

The elephants, camels, and horses are sometimes known as strong pieces. When one side loses two such pieces, an opposing dog might then be considered a strong piece, as it faces threats from only two enemy pieces.

Swarm[edit | edit source]

When several pieces advance toward an away trap. A swarm may allow an advanced elephant to rotate out of a trap control fight, or out of hostage defense. See also Trap attack.

Three-for-one[edit | edit source]

Three steps which can be undone in a single step by the opponent. Such a move will give away time, unless the opponent can't easily spare that one step.

Three-for-three[edit | edit source]

Three steps which could be undone in three steps by the opponent. When three steps cancel three steps, both sides have effectively taken one-step turns. This may continue for several turns, as long as the fourth steps sometimes create unique positions.

Trap[edit | edit source]

There are four trap squares on the board, located at c3, c6, f3 and f6. A piece can be captured in a trap square.

Trap attack[edit | edit source]

A trap attack entails an attempt to occupy multiple key squares of an away trap, perhaps creating strong capture threats.

Turn[edit | edit source]

A player completes a turn by moving pieces a total of one, two, three or four legal steps. The opposing player then gets a turn. Also known as a move.

West wing[edit | edit source]

The left side of the board viewed from Gold's perspective, specifically the a-, b-, and c-files.