rhd robin - sort of

[redbeard]

we have ten teams that have to play each other twice in the short amount of time possible but not at the same site.  Last year we had 9 teams and we sent 3 teams to 4 different sites and managed to get done in 4 weeks.  These are high school teams and 6 games per site is all we can do in an evening.  Now we have 10 teams and we're not sure how to schedule these in the shortest amount of time.  We would really appreciate any help anyone ccould give.  Thanks.

[Ian Wakeling]

Please would you describe is some more detail what you did last year.  Are all the teams required to play on the same evenings?  I am thinking the optimal approach might be to use only two sites per evening. On each evening where there is play, 5 teams go to one site, the remaining 5 teams go to another site.  At a site you hold 6 games, each team having either two or three matches. Is that what you had in mind?

Ian.

[redbeard]

Sorry, I didn't explain myself very well.  Each game takes between 30 and 45 minutes. so the administration only wants a max of 6 to be played after school in the evening.  Last year each team played every other team twice.  So this is kind of a double round robin.  There were 3 sites and 3 schools went to each site once a week.  This way all the games were played in a 4 week period.  This worked with 9 teams.  However, with 10 teams this no longer works.  The administration would like to still get these double games played in a 4 week period, but I don't think it can be done.  I would appreciate any comments you might have.  Thank you for your time.

[Ian Wakeling]

Playing a double round robin with 9 teams, you have a total of 72 matches to play.  On each week of the tournament you divide the 9 teams into 3 groups of 3 and each group is sent to a particular site.  At any one site the three teams who meet can play only 3 matches (A vs B, A vs C, and B vs C).  Over 4 weeks this gives a total of 4 weeks x 3 sites x 3 matches=36 matches.  This is a long way from the 72 matches that you say you played, so what have I not understood?  Do all teams play on two evenings each week?

With 10 teams you will need 90 matches for the double round robin. My suggestion above of dividing the 10 teams over two sites on the same evening means you could play 12 matches an evening (provided that you always played 6 matches at a site).  So playing 2 evenings a week would mean that it is still possible to complete within the 4 week time limit.

Ian.