Round Robin Tournament Scheduling

13 teams, 8 games

Lonneke · 4 · 2826

Lonneke

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on: July 10, 2007, 06:56:35 AM
Hi,

I am organizing an event with 8 different games. There are 13 teams. Each game can host two teams. There are two games that can host three teams (if that would make finding a solution easier). Each team has to play each game exactly once. I would like to have different teams playing each other as much as possible. It would be nice if the number of rounds stays close to 8. Can you please help me with finding a good schedule?

Thanks a lot,
Lonneke


Ian Wakeling

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Reply #1 on: July 12, 2007, 04:10:24 AM
If you restrict yourself to playing only matches involving two of the teams, then I can provide a potential solution. But there is a problem as the number of teams is odd,  with one bye per round and only 8 rounds, 5 of the teams will never get a bye and end up playing one more match than the others.

If you start with the scedule below for 14 teams.


 G1     G2     G3     G4     G5     G6     G7     G8
(A I)  (H J)         (G K)  (F L)  (E M)  (C D)  (B N)
(C N)  (B I)  (A J)         (H K)  (G L)  (F M)  (D E)
(E F)  (D N)  (C I)  (B J)         (A K)  (H L)  (G M)
(H M)  (F G)  (E N)  (D I)  (C J)         (B K)  (A L)
(B L)  (A M)  (G H)  (F N)  (E I)  (D J)         (C K)
(D K)  (C L)  (B M)  (H A)  (G N)  (F I)  (E J)      
       (E K)  (D L)  (C M)  (A B)  (H N)  (G I)  (F J)
(G J)         (F K)  (E L)  (D M)  (B C)  (A N)  (H I)


Now delete all matches involving team K and you have a schedule where no two teams are matched together more than once and 12 out of 13 teams play each game. You could add in two more rounds to make sure everyone plays every game, but it will not be pretty.  Things would be much better if you could find a 14th team.

Ian.


Lonneke

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Reply #2 on: August 28, 2007, 09:14:43 AM
Dear Ian,

Thanks a lot for your help! I started to work out your suggestion, but now one team withdrew. So instead of 13 teams, I have only 12 teams left. I hope that that means that we can play the 8 games in 8 rounds without any bye's. But I can't easily transform your scheme for 14 into one for 12. Would it be a lot of effort to help once more by showing me the scheme for 12 teams?

Kind regards,
Lonneke


Ian Wakeling

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Reply #3 on: August 30, 2007, 04:56:08 AM
Dear Lonneke,

Here is a schedule for 12 teams.  As before no team plays another more than once.


  G1     G2     G3     G4     G5     G6     G7     G8
(B I)  (A J)  (G K)  (F L)  (H E)  (D C)
       (C I)  (B J)  (H K)  (G L)  (A F)  (E D)
              (D I)  (C J)  (A K)  (H L)  (B G)  (F E)
(G F)                (E I)  (D J)  (B K)  (A L)  (C H)
(D A)  (H G)                (F I)  (E J)  (C K)  (B L)
(C L)  (E B)  (A H)                (G I)  (F J)  (D K)
(E K)  (D L)  (F C)  (B A)                (H I)  (G J)
(H J)  (F K)  (E L)  (G D)  (C B)                (A I)


No more withdrawers I hope!

Kind regards,

Ian.