The Arimaa challenge was won in 2015, when the bot Sharp won matches against three top human players.
The second strongest of the six unique Arimaa pieces.
See Trap (verb).
The fifth strongest of the six unique Arimaa pieces.
When a player's own Rabbit is used against them to help blockade a major piece. This is done by placing the Rabbit behind the major piece so that the Rabbit blocks movement in that direction. The major piece is said to be choked.
The fourth strongest of the six unique Arimaa pieces.
The right side of the board viewed from Gold's perspective, specifically the f-, g-, and h-files.
The strongest of the six unique Arimaa pieces. The Elephant is the only piece that cannot be pushed or pulled by the enemy.
A player wins the game by elimination if the opposing player has no Rabbits left.
Occurs when each side traps a piece of equal strength, usually within a short period of time. For example, if each side captured a Rabbit on consecutive moves it is described as a Rabbit Exchange. See also Trap (verb).
When two pieces adjacent to a trap appear to be mutually protected, but in fact, both are in danger of being trapped due to strong enemy pieces adjacent to them. See also Mutual Protection.
The combination of pulling and pushing an opponent's weaker pieces such that the weaker piece appears to be flipped to a different side of the stronger piece. Weaker pieces are vulnerable to being flipped to the opponent's side and eventually being trapped. Two special cases are sometimes called Swing and Throw.
A fork occurs if a piece is simultaneously threatened with capture in two different traps. This can only occur on the squares c4, c5, d3, d6, e3, e6, f4 and f5.
A four-step move making a change to the position which can be undone in two steps by the opponent. Four-for-twos are seldom good moves.
A piece is frozen if it is adjacent to a stronger enemy piece and is not adjacent to any friendly pieces. A frozen piece cannot move until the enemy piece moves away or a friendly piece moves onto an adjacent square.
A player wins the game by goal if one of his/her Rabbits advances to the opponent's home rank.
The player with the Gold pieces is both the first to setup and the first to move. See also Silver.
The third strongest of the six unique Arimaa pieces.
A player wins the game by immobilization if the opposing player has no pieces remaining or is unable to make a single legal move. See also Blockade
When a player uses two or more pieces to take control of an opponent's home trap by not allowing the opponent access to three or all four squares adjacent to the trap. The opponents pieces near that trap usually scatter. See also Scatter.
When a computer program gets triggered to sacrifice a series of minor pieces such as Rabbits, Cats or Dogs to prevent a stronger hostage piece such as a Horse or Camel from being captured. Typically the computer will recognize that the strong piece is in danger and send over a weak piece to try to help, only to have the weak piece captured with nothing to show for it. The cycle then repeats, with the computer repeatedly sending over weak pieces and the opponent repeatedly capturing them.
A formation usually at the edge of the board where two friendly pieces are diagonal to one another such that if either is pulled one step it remains unfrozen due to the other friendly piece and can easily return to its original place.
A lone friendly piece that is supporting a framed piece is said to be pinned. See also Frame.
When group of friendly pieces come together and form a T shape to prevent a stronger enemy piece from pushing the weaker piece at the top center of the T.
A slow game in which the players are allowed a specified number of days (sometimes hours) to complete each move. Historically postal games (e.g. chess, go) were played by old-fashioned mail and a single game could last for years. Nowadays, postal games are normally played online in a period of weeks or months. Also known as a correspondence game.
A player can pull an enemy piece with a stronger piece by first moving the friendly piece to one of the unoccupied adjacent squares and then moving the opponent's piece into the square that was just vacated. A pull requires 2 steps. See also Step.
Pull and replace
A four-step move where a strong piece pulls an opponent's piece, and a weak friendly piece occupies its former position, with the strong piece returning to its initial square.
A player can push an enemy piece with a stronger friendly piece by first moving the opponent's piece to one of the adjacent squares and then replacing it with the friendly piece. A push requires 2 steps. See also Step.
Push and replace
A somewhat less common variant of pull and replace.
A quarter of the board (16 squares), usually distinguished either by the trap square it contains, or by compass directions from the perspective of Gold. Thus the c6-quadrant is also the northwest quadrant, etc.
The weakest unit on the board and the only piece that cannot move backwards. However, Rabbits are extremely important due to their ability to win the game by goal. See also Goal.
One of eight rows on an Arimaa board. Gold begins the game with 16 pieces on the first and second ranks while Silver beings with 16 pieces on the seventh and eighth ranks. The home rank for Gold is 1, while Silver's is 8.
If a player allows a friendly piece to be trapped in order to pursue a strategic objective elsewhere on the board, the friendly piece is said to be sacrificed.
When a player's home trap is invaded the pieces near that trap move away to avoid being captured. See also Invade.
The player with the Silver pieces is second to setup the pieces and second to move. See also Gold.
There are six unique types of pieces, each with a different strength. Stronger units can push, pull and freeze any weaker enemy pieces. From strongest to weakest, the units are Elephant, Camel, Horse, Dog, Cat, Rabbit. See also Freeze, Pull, Push.
Three steps making a change to the position which can be undone in one step by the opponent. Three-for-ones are usually not good moves.
Three steps making a change to the position which can be undone in three steps by the opponent. If this happens, both players are effectively making one-step moves, since the three reversible steps can be ignored. This may continue for several moves.
There are 4 trap squares on the board located at c3, c6, f3 and f6. Pieces that occupy these four squares may be trapped. See also Trap (verb).
A piece is trapped and removed from the board if it occupies a trap square and there are no friendly pieces occupying any of the four adjacent squares. If there is a friendly piece on an adjacent square, then it is possible for a second piece to safely walk over - or occupy - on a trap square. A trapped piece can also be described as being captured. See also Trap (noun).
A player completes a turn by moving pieces a total of one, two, three or four legal steps. The opposing player then makes his/her turn. Also known as a move. See also Step.
The left side of the board viewed from Gold's perspective, specifically the a-, b-, and c-files.