The 2010 Arimaa Open Classic and World Championship

Overview: Each year a tournament is held to determine the best human Arimaa player in the world. The tournament is conducted in two phases. First there is a swiss format tournament which is open to everyone and referred to as the Open Classic or preliminary. The top 8 performers from this phase move on to the second phase which is a floating double elimination format tournament referred to as the World Championship or finals.

Schedule:
Registration begins Nov 1, 2009
Registration ends 6PM EST Friday Jan 1, 2010
Ratings fixed 6PM EST Saturday Jan 2, 2010
First round begins Tuesday Jan 5, 2010; with one round per week
Tournament ends Late March 2010

Prizes:

Registration: Interested players should register before the deadline mentioned above. There is a registration fee of $20 USD which will be returned if you do not forfeit or drop out of the tournament.

Resigning: There is no penalty for resigning a game, however resigning is discouraged and completing a game to the end is highly encouraged.

Commemorative Gear: Commemorative World Championship T-shirts listing the names of all participants and match-ups will be available for purchase after the event.

Location of games: All games will be played in the Arimaa gameroom over the Internet. The players are responsible for providing their own reliable computer and Internet connection. There will not be a rematch if a player loses a game due to problems with their computer or Internet connection or even the game client program. However, if there is a problem with the game server, the tournament director will consider a rematch.

Time of games: The players will play one game per week. The players will submit a web form to indicate what times they are available to play during the upcoming week. If a player does not submit the preferred times then any preferred times they had previously submitted will be used. If no preferred times have been provided then any time will be considered a preferred time. After 7pm EST Monday the players will be notified of the opponent they have been paired with for that round along with the tentative time of the game. The players will have 24 hours to communicate with each other and update their times. On Tuesday 7pm EST the tournament coordinator will run the scheduler to fix the final game time and notify both players of the scheduled game time. The earliest a game could begin is on 7pm EST Wednesday and the latest is on 5pm EST the following Monday. The final game times cannot be changed.

Forfeits: If a player does not show up for the game within 15 minute after the scheduled start time then that player will lose by forfeit. To claim the forfeit the player that showed up just needs to exit the game window after the 15 minutes are over. However, the player can choose to give the opponent more time by keeping the window open. A player losing by forfeit may not appeal for a rematch regardless of the reason for being late. Also the player who forfeits a game is automatically removed from the tournament and will not play in future rounds unless the tournament directors accepts the appeal.

Tournament format: Swiss preliminary to select the top 8 performers followed by a Floating Double Elimination final

    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 for the Swiss preliminary attempts to best meet the following objectives:

    1. The number of rounds to be played is determined by the number of participants and is declared before the start of the Swiss. The following table is used to determine the number of rounds.
      # of players  # of rounds  # of wins needed
      1-800
      9-1131
      12-1542
      16-2353
      24-3564
      36-5575
    2. The players are initially ranked based on higher WHR ratings. Ties broken by lower gameroom rating uncertainty then further broken by greater number of games played and finally by older joined date/time.
    3. Two players may play each other only once.
    4. Players are paired with others of the same score, or nearest score.
    5. Color assignment is done as described in a later section.
    6. The player order is determined by the aggregate of points won: 1 point for a win and 0 point for a loss (draws are not possible). A player whose opponent fails to appear for a scheduled game receives a win and the opponent a lose. Ties are broken by sum of opponent score from highest to lowest. Ties are further broken by pre-tournament rating from highest to lowest. Ties are further broken by unique random number assigned at start of round.
    7. Sum of opponent score (SoS) is calculated as follows:
        P = wins[this player]
        foreach opponent in list_of_opponents[this_player]
          O = wins[opponent]
          T = 1/(1+10^(F*(P-O)/(N+1)))
          SoS += T
      
        where:
          N = Number of rounds that have been played
          F = factor determined by the standard deviation of player ratings
            = 0.5 + stdev(player_ratings)/100
      
    8. Pair the players from the top of the list to the bottom as follows: If the player is in the top half of the score group and has not already been paired then try to pair the player against the player in the bottom half of the score group starting at the same relative position in the bottom half as the player is in the top half. If a pair cannot be made then continue down the list within the same score group. After reaching the bottom of the score group then work upwards within the same score group. If a match cannot be found within the same score group then work down the list starting from the top of the next score group.
    9. If the player is in the bottom half of the score group and has not already been paired then pair the player against the next player below them in the list and continue down the list until a pair is found.
    10. If there is a an odd number of players the player at the very bottom of the list gets a bye.
    11. All games are played according to the Arimaa Match Rules.

    The pairing algorithm for the Floating Double Elimination attempts to best meet the following constraints:

    1. Players are initially ranked based on performance in the Open Classic. Ties broken by WHR ratings.
    2. Everyone plays until they have lost two times. At the end of each round, any player who has lost for the second 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. Minimize the number of pairings occurring for the Nth time. ...
    5. Minimize the number of pairings occurring for the fourth time.
    6. Minimize the number of pairings occurring for the third time.
    7. Minimize the number of pairings occurring for the second time.
    8. Give the bye to the player with the fewest losses.
    9. Give the bye to the player with the best ranking in the preliminary.
    10. Minimize the number of pairings between players whose number of losses differ by N, etc.
    11. Based on a ranking of the non-eliminated players primarily by least number of losses and secondarily 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.
    12. Color assignment is done as described later considering all games including the Swiss preliminary.
    13. All games are played according to the Arimaa Match Rules.

    This tournament format is designed only to clearly recognize a first place winner. Recognition of second and third place will be done based on number of games won. In case of ties for second place addition games will be played to break the tie. A two-way tie for second will be broken by a one-game playoff. A three-way tie for second will be broken by first pairing the two players eliminated in the second-to-last round and the winner playing the last eliminated player. A two-way tie for third will be broken by a one-game playoff. In these tie breaker games the colors are assigned as described in the next section considering all games including the Swiss preliminary.

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 Swiss preliminary will be played with a time control of: 60s/5m/75/0/4h/4m. All games in the FDE final will be played with a time control of: 90s/5m/75/0/6h/5m.

Notes:

1 The gift certificate from Z-Man Games must be used in one order. If the order amount including shipping exceeds the value of the gift certificate the difference must be paid for separately. The gift certificate is not transferable. The order should not be placed through the online shop (though you can use that to check prices and availability). A special contact address will be provided to redeem the gift certificate.

2 The gift certificate from Boardgames 4 Us must be entered online at the www.boardgames4us.com web site to receive credit. It may not be used for phone or mailed orders. The gift certificate cannot be redeemed for cash. The gift certificate is transferable and unused credit may be used in future orders.

3 The discount code from Boardgames 4 Us must be entered online at www.boardgames4us.com at the time of purchase. The discount code must be used during the time period specified with the code and can be used for multiple orders.

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