The 2009 Arimaa Open Classic and World Championship

Overview: The 2009 Arimaa Open Classic and World Championship tournament will determine the best human Arimaa player. The tournament is open to all human player regardless of skill level. The tournament will begin on Tuesday January 6th, 2009 and finish by mid March (depending on number of participants).

Prizes:

• 1st place winner will receive: official Arimaa World Champion certificate, $100 cash prize; $100 gift certificate towards purchase of games from Z-Man Games¹.
• 2nd place winner will receive: $50 gift certificate towards purchase of games from Z-Man Games¹.
• 3rd place winner will receive: $25 gift certificate towards purchase of games from Z-Man Games¹.
• All participants will receive a prize of $1 for each game they win in the preliminary and $5 for each game they win in the finals.

Registration: Interested players should register before the deadline of 6PM EST Friday January 2nd, 2009. There is a registration fee of $20 USD of which $10 USD will be returned if you do not forfit, resign or drop out of the tournament. Commemorative World Championship T-shirts listing the names of all participants and match-ups will be available after the event for $20 USD.

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. At 8pm (EST) Sunday January 4th, 2009 the players will be notified of the opponent they have been paired with. The players will have 24 hours to submit a web form to indicate what times they are available to play during the upcoming week between Tuesday and Sunday. If a player does not submit this within the allowed time 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. On Monday 8pm (EST) the tournament coordinator will fix the game time based on the input from both players and notify them of the scheduled game time. The earliest a game could begin is on Tuesday and the latest is on Sunday. 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 forfiet 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 forfiet may not appeal for a rematch regardless of the reason for being late. Also the player who forfiets 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
   1-8	0	0
   9-11	3	1
   12-15	4	2
   16-23	5	3
   24-35	6	4
   36-55	7	5

2. The players are initially ranked based on gameroom ratings.
3. Two players may play each other only once.
4. Players are paired with others of the same score, or nearest score.
5. When possible, a player is given the gold pieces as many times as he is given the silver pieces.
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. 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 upwords 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.
8. 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.
9. Within each pairing the player who has played a color fewer times plays that color. If both players have played a color the same number of times then the color is assigned randomly.
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 gameroom 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 occuring for the Nth time. ...
5. Minimize the number of pairings occuring for the fourth time.
6. Minimize the number of pairings occuring for the third time.
7. Minimize the number of pairings occuring 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. Pair players with a similar number of losses against each other.
11. Maximize the sum of the squares of the differences in rank among remaining players.
12. Within each pairing, the player who has played gold a fewer number of times so far against this opponent will play gold for that game. If this is a tie, then the player who has played gold a fewer percentage of times so far in the tournament will play gold for that game, with ties broken randomly.
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 so that a player plays the color they have played a fewer number of times. If this is equal then the player with the lower raking at the start of the tournament selects the color.

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:

• The games must be played in one sitting and cannot be adjourned.
• A player will not be allowed to take back a move once it has been submitted.
• The games will contribute to the players' ratings.
• Players are forbidden from using advice or suggestions from others or programs while playing the games. Any player doing so will be eliminated from the championship matches and will not be allowed to take part in future matches.
• The tournament coordinator will carry out the tournament in compliance with the stated rules and does not make any decisions that will effect the course of the tournament. A player may serve as the coordinator.
• The tournament director will serve as the arbitrator in case of disputes. Should a dispute arise about the outcome of a game, the director will review the game and decide if the game should be replayed. A player may not serve as the director.
• The director will also make the final decision on matters of pairing and color assignment. However, the pairings and color assignments are done as much as possible using a program and the need for intervention should be rare.
• The director may require any player to have a web-cam turned on for monitoring during the games. Also the director may send a representative to be present with any player during the games. A player who does not comply will lose by forfeit.
• All decisions made by the director shall be considered final and binding by all parties.
• Omar and Aamir Syed reserve the rights to modify the championship tournament details in the future to resolve any logistical problems that may arise.

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 certifiate the difference must be paid for seperately. 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.

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