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Amazons, (Game of the Amazons, El Juego de las Amazonas)
a two-player abstract strategy game invented in 1988 by Walter Zamkauskas of Argentina [1] . El Juego de las Amazonas is a trademark of Ediciones de Mente. In 1998 and 1999, Hiroyuki Iida organized the first two computer Amazons championships, which were held at the Computer Games Research Institute of Shizuoka University [2] [3] . Computer Amazons is played at the Computer Olympiad since London 2000. Amazons is usually played on a 10 x 10 board, but can be played on boards of arbitrary size.

The two players, White and Black are each given four amazons in predefined locations. A supply of markers (checkers, poker chips, etc.) is also required. White makes the first move with one of his amazons, which move like a queen in chess, except captures. Each move contains two mandatory parts, moving the amazon and throwing an arrow from its target square to one of its attacked empty squares, which is marked and permanently blocked. Amazon and the arrow can't land on or cross over any own or opponent amazon or arrow. The last player to be able to make a move, which includes throwing an arrow, wins.
Position after 1.d1-d6/g9 [4]

Computer Olympiads

Selected Programs

Gold medalists from the Computer Olympiad


Maastricht 2002

Maastricht 2002 winners, Richard J. Lorentz, Jens Lieberum, Johan de Koning [5]

Yokohama 2013

Yokohama 2013 award ceremony [6] , Richard J. Lorentz, Johan de Koning, Jaap van den Herik [7]

Branching Factor

excerpt of Patrick Hensgens' 2001 master's thesis [8] :
In the initial position the first player has 2176 possible moves. This is a huge number, especially when compared to other AI games, where most games have a branching factor below 50 in the initial position (e.g., Chess 20, Lines of Action 36, Checkers 7, Draughts 9). Fortunately the branching factor in the game of Amazons decreases rapidly as the game progresses. In the endgame the branching factor is usually below 50.

Investigating the average branching factor of Amazons, we encounter a strange phenomenon. From the experiments we performed for finding the average branching factor we observed that this number is quite different for both players. The first player has an average branching factor of 374 while the second player has an average branching factor of 299. This means that to compute the game-tree complexity we need a formula that takes into account that both players have a different branching factor.

Furthermore, we observed that the average branching factor for both players increases with decreasing playing strength of both players.

Selected Publications

[9] [10]


2000 ...


2005 ...

2010 ...

External Links




  1. ^ Game of the Amazons from Wikipedia
  2. ^ Nobusuke Sasaki, Hiroyuki Iida (1999). Report on the First Open Computer-Amazons Championship. ICCA Journal, Vol. 22, No. 1
  3. ^ Hiroyuki Iida, Martin Müller (2000). Report on the Second Open Computer-Amazons Championship. ICGA Journal, Vol 23, No. 1
  4. ^ Game of the Amazons from Wikipedia
  5. ^ ICGA: Amazons by Richard J. Lorentz
  6. ^ Games Tournament 2013 - Amazons, ICGA
  7. ^ Photos 2013 Events: day 6, ICGA
  8. ^ Patrick Hensgens (2001). A Knowledge-based Approach of the Game of Amazons. Master's thesis, Maastricht University, pdf
  9. ^ Publications related to the game of Amazons, University of Alberta
  10. ^ ICGA: Amazons by Richard J. Lorentz

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