# Geek Trivia: What descendant game of chess was designed specifically to stifle artificial intelligence?

What descendant game of chess -- played with all the same pieces on a standard chess board -- is specifically designed to be difficult for computers, even supercomputers, to play?

The game is called Arimaa, and it was designed by software engineer and artificial intelligence developer Omar Syed as a response to Deep Blue's original defeat of Kasparov in 1997. Arimaa, named for Syed's son Aamir, uses all the standard chess pieces and a standard chessboard, but has rules that are designed in direct opposition to artificial intelligence's chess computing techniques.

The standard chess side of one King, one Queen, two Knights, two Rooks, two Bishops, and eight Pawns become one Elephant, one Camel, two Horses, two Dogs, two Cats, and eight Rabbits, listed in order of strength. The goal of Arimaa is to advance your rabbits to the opposite side of the board, while preventing your opponent from doing the same. Four squares near the center of the board — c3, f3, c6, and f6 — are "trap" squares that you can force opposing pieces into to remove them from the board. An opponent's piece must be pushed or pulled into a trap square by a stronger piece, so a Horse could move a Dog or Cat, but not a Camel or Elephant.

The Arimaa rules of setup and movement are where the supercomputer thwarting comes in. During setup, a player may choose to arrange his 16 Arimaa pieces in any configuration along the nearest two rows of the board. This lack of standard starting position means Arimaa software can't have a reasonable "opening book" of moves, as there simply too many possible combinations to model when combined with the movement rules.

As to movement, a player has four one-space movements to "spend" per turn, though he may not spend all of them. Pieces can move to any empty space left, right, forward, or backward, and the moves can be spent on multiple pieces — your Camel moves one space forward, one Horse two spaces left, and a Rabbit one space back. Moving into a space occupied by a weaker opposing piece pushes it in the direction of the move, so long as the destination space is empty.

Thus, the sheer number of possible move permutations is astronomically higher in Arimaa as compared to chess. In chess, any given board position represents roughly 35 potential moves. In Arimaa, every board position offers roughly 17,000 potential moves. Generally, for every eight chess turns a program could model, an Arimaa program could only model about three. There goes the computing advantage.

In 2002, Syed began offering a \$10,000 prize to any programmer who can develop an Arimaa program that can beat a top-three player in a best-of-three match by 2020. In 10 years, no one has claimed the cash.

That's not just some binary-bamboozling braggadocio, it's a computationally confounding construct of Geek Trivia.

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