Round Robin Tournament Scheduling

Whist for odd number

beachvolleyball

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on: August 23, 2010, 01:32:47 PM
First, I originally posted this in the "comments" section.  Sorry for that.  

Now, for my question:  I need to create a whist tournament (pairs of pairs) for 9 people- so one person will have a bye each round.   I haven't found a way to ensure every person plays with every other person, and against every other person the same number of times.  I don't believe there is a way to do this.  But, I need to create a table that comes as close to this as possible.  Thanks for any advice!  I'm stumped.  Closest I've come is a case where one person plays against a particular competitor 3 times, and someone else doesn't play them at all!

I received a response (again in the comments section- sorry!), that indicated 9 rounds were needed, which I guess is correct.  Even with 9 rounds, I realize it may not be mathematically possible, but I need to get as close as possible to a fair tournament given the following:  a) Each person must be paired with each of the other 8 people exactly once, and b) Getting as even as possible who each person faces on the opposing team, and how many times they face them.  Thanks.


beachvolleyball(Guest)

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Reply #1 on: August 23, 2010, 12:07:32 PM
[Original message from comments area]

I need to create a whist tournament (pairs of pairs) for 9 people- so one person will have a bye each round.   I haven't found a way to ensure every person plays with every other person, and against every other person the same number of times, in an 8-round tournament.  I don't believe there is a way to do this.  But, I am limited to 8 rounds, so I need to create a table that comes as close to this as possible.  Thanks for any advice!  I'm stumped.  Closest I've come is a case where one person plays against a particular competitor 3 times, and someone else doesn't play them at all!
« Last Edit: August 24, 2010, 03:06:51 AM by Ian »


wbport

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Reply #2 on: August 23, 2010, 12:18:24 PM
[Reply moved from comments area]

For nine players in a round robin, nine rounds are required since someone (or team) must sit out each round.  I would suggest a swiss guided round robin.  After the first round, choose a round in the rest of a round robin table which matches your then undefeated teams together.  After about four or five rounds of this randomly select the remaining round to be omitted and play the rest of them in order.

By the way, please make requests like this in the Requests forum as there is no opportunity to answer your request in it's own thread.  In the comments section, only new threads are allowed.
« Last Edit: August 24, 2010, 03:15:24 AM by Ian »


Ian Wakeling

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Reply #3 on: August 24, 2010, 03:10:14 AM
You can find Whist schedules for 4n+1 players on J D A Wiseman's website.  In particular the balanced solution for 9 players in in 9 rounds is possible, so simply remove one round from this schedule if you are limited to 8 rounds.


beachvolleyball

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Reply #4 on: August 24, 2010, 11:18:40 AM
Fantastic!  That's it!

Thanks Ian.