The 2015 Arimaa World Computer Championship

Overview: Each year a tournament is held to determine the best computer Arimaa player in the world. The tournament is conducted in two phases. First there is a qualifier in which the entrants bots play against bots from previous years. The top 8 performers from this phase move on to the second phase which is a floating quad elimination format tournament referred to as the World Computer Championship or the finals. The top two finishers from the finals will compete for the right to play in the Arimaa Challenge match.

Registration begins: 7PM EST Dec 1, 2014
Registration ends: 7PM EST Dec 31, 2014 (last day of Dec)
Qualifying period begins: 7PM EST Jan 1, 2015 (games must start after this time)
Qualifying period ends: 7PM EST Feb 1, 2015 (games must finish before this time)
Top 8 qualifying bots determined: Feb 1, 2015
Linux account provided for top 8 bots: Feb 8, 2015
Program uploaded to server by: 7PM EST Feb 22, 2015
Programs tested by organizer: Feb 28, 2015 (account access disabled after successful testing)
Tournament begins: Mar 1, 2015
Tournament ends: Mar 15, 2015

Prizes: The Prize Fund will be divided by the number of games in the tournament and that amount will be awarded to the winner of each game. The 1st place winner will also receive the title of Arimaa World Computer Champion via an official certificate.

Registration: Interested developers should register as soon as possible to identify themselves and the name of the bot they will be registering. Only one bot is allowed per developer or development team. There is a registration fee of $10 USD which is added to the prize fund.

Penalty: There is a penalty of $20 USD which must be paid if you break any of the qualifying phase rules or do not upload your bot before the deadline if you qualify.

Qualifying: Even if less than 8 bots have registered for the computer championship, a qualifying phase is needed to determine the initial ranking in the finals. During the qualifying phase the qualifying bots will try to win games against a stable of benchmark bots available on

The benchmark bots for 2015 will be:

During the qualifying phase the bot developers must run their programs on standard off-the-shelf hardware that is not more than approximately five times in performance to that which was used for the challenge match in the previous year. Developers which qualify by means of using much faster hardware or other assistance that makes their bot play far better in qualifying than in the championship will forfeit their prize money and be disqualified from future Arimaa World Computer Championship events for two years in addition to paying the penalty for violating the qualifying rules.

During the qualifying period a qualifying bot may play each benchmark bot up to twenty times; additional games will be ignored. Each benchmark bot must be played with alternating colors. A qualifying bot scores one point for each win in its longest winning streak against a benchmark bot, up to a maximum of four points per benchmark bot. The best possible qualifying score is 24 points, which represents attaining a four or more game winning streak against each benchmark bot. Only rated games will count towards the score; unrated games will be ignored. Only games with alternating color will count; non-alternating color games will be ignored even if they are rated. The first game played against a benchmark bot sets the color for subsequent games against that bot.

For bots which tie on qualifying score, the first tie-breaker is zero minus the losses prior to longest winning streak with each bot. Losses after the longest winning streak are ignored. Thus, the best possible tie-break score is zero, which represents winning all qualifying games and not playing any excess games. The worst possible tie-break score is -120, which represents playing the maximum number of games and winning none. The second tie-break is earliest date of completion, i.e. the bot whose last game which counts towards the score was finished first.

Developers are responsible for having a stable Internet connection to during qualification. Games decided by network failures or other technical issues will count in the qualification standings.

Bots which have not played any qualifying games will be ranked below the bots that have played qualifying games. If more than one bot has not played qualifying games then the gameroom ratings will be used to rank the bots in the section that has not played any qualifying games.

Program Submission: The developers of the top eight bots from the qualifier will be given accounts on a Linux computer to port and setup their programs before the final tournament begin. If a bot that have qualified is not uploaded and properly setup by the deadline it will be disqualified and the next highest scoring bot from the qualifier will be invited to replace it and given only 6 days to be uploaded and tested. The invited bot developer does not risk losing the registration fee if the bot cannot be setup in the given time. Bots that were submitted in previous years may be used if the invited bot from the qualifier cannot be setup in time.

Once the programs have been submitted for the tournament, they may not be modified manually, but can modify themselves if it can be done as an automated process. Such an automated process will be setup to run as a cron job during the night between one round to the next. The process should not run for more than four hours. The process will be sharing resources with other processes that may be running at the same time.

Program Requirements All programs submitted for the tournament must:

Tournament format: Floating Quad Elimination

In the finals the programs will be played against each other under the control of the tournament coordinator. The games will be played in the Arimaa gameroom. Each program will run on it's own computer and both computers will have the exact same hardware and OS configuration. The tournament coordinator runs a program which is used to pair the players, assign a bye in rounds with odd number of players and to select the color of each player. The pairing algorithm attempts to best meet the following constraints:

  1. Programs are initially ranked based on the score from the qualifying phase.
  2. Everyone plays until they have lost four times. At the end of each round, any player who has lost for the fourth time is eliminated.
  3. If an odd number of players remain, the bye must go to some player among the players with the fewest byes so far.
  4. For every number N, minimize the number of pairings occurring for the Nth time, without regard for any number of pairings occurring less than N times.
  5. Give any bye to a player with as few losses as possible.
  6. For every number N, minimize the number of pairings between players whose number of losses differ by N, without regard for any number of pairings between players whose number of losses differ by less than N.
  7. Calculate tournament performance ratings for all players on the basis of the Bradley-Terry model and all past games including those in which one player forfeited, but not both, plus, for each player, a virtual half-weighted draw against a fixed dummy player, identically rated against everyone. No existing ratings are used in the calculation.
  8. Give any bye to a player with an as high as possible tournament performance rating.
  9. Give any bye to a player who is as best seeded as possible.
  10. Based on a ranking of the non-eliminated players primarily by least number of losses, secondarily by tournament performance rating and thirdly by seed, maximize the sum of the squares of the differences in rank among paired players with equal number of losses minus the sum of the squares of the differences in rank among paired players with different number of losses.
  11. Color assignment is done as described later.
  12. All games are played according to the Arimaa Match Rules.

This tournament format is designed only to clearly recognize a first place winner. Ties for second place will be broken by adding one more life to all the second place players and continuing the tournament taking into account the earlier games of the tournament with respect to byes, pairing, color and seeding. Recognition of third place will be done based on number of games won. Ties for third place will not be broken with additional games and all players that tied for this position will be recognized.

Color Assignment:
Color assignment within each pairing will be made on the basis of games each player has played within the tournament, including forfeits. The rules are given in order of strict priority, i.e. a later rule will apply only if no prior rule distinguishes between the players.

  1. Assign Gold to the player with a lower total of previous games as Gold minus previous games as Silver.
  2. Assign Gold to the player with fewer previous games as Gold among games between the two players.
  3. Break both color streaks. If possible give both players a different color then the color they played with in their most recent game.
  4. Break the color streak of the player with the longer streak.
  5. Swap colors with respect to the last time the two players played against each other.
  6. Assign color arbitrarily.

Time Controls: All games in the finals will be played with a time control of: 2m/6m/100/0/8h/6m.

Hardware and OS: The hardware and OS that will be used in the championship tournament and challenge match will be specified shortly before the tournament begins. The hardware will typically be a standard general purpose computer that can be purchased within $1000 USD (not including tax, shipping and handling :-). The OS used for the Arimaa challenge will be the most current version of the Linux OS.

Technical Problems: Technical failures on during tournament games will be remediated as follows:

  1. Once the first game of a round has started, the results of previous rounds can't be altered, no matter what issue is discovered.
  2. If it is determined during a game that either bot has suffered a disadvantage, the game will be immediately halted, made unrated, and resumed from the point at which the disadvantage first occurred. The game must be halted regardless of whether the disadvantaged player is winning or losing.
  3. If it is determined after a game is over, but before the next round has begun, that either bot has suffered a disadvantage, the game result will be invalidated, the game will be made unrated, and the game will be replayed from the point at which the disadvantage first occurred. The game must be replayed whether the disadvantaged player won or lost.
  4. Disadvantages that warrant a game being halted and/or replayed include, but are not limited to:
    1. Extraneous processes running on either tournament server
    2. The game server failing to receive a move sent by a tournament server
    3. A tournament server failing to receive a move sent by the game server
    4. A tournament server stopping and restarting a bot mid-move
    5. A bot being misconfigured by the tournament coordinator
  5. The tournament director decides whether technical failures not on this list warrant halting and/or replaying games.
  6. When restarting games from a specific position, the tournament coordinator will attempt to restore the clock state (reserve times and game time) as closely as possible to the state at the time the issue occurred.

Publication: The intent of the Arimaa computer championship and challenge match is to help advance research in areas of AI. Thus, it is recommended that the participants (especially those with programs in the championship tournament) submit an article to the ICGA technical journal describing their research and results. Also the programs submitted for the championship tournament will be made available for others to play against in the public Arimaa gameroom after the challenge match is over. Thus the programs and players participating in the following years can be improved against the best programs of the previous years. Participants who submit programs that are limited after some time, some games or limited in any manner will not be allowed to participate in following years and must return any prize awarded. Organizations or individuals who are not comfortable with these conditions should not participate.


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