12 player doubles mixed partners

[Lollylegs]

I have a social table tennis tournament to organise. I have been reading through this site & a million other places on the internet, but haven't found anything that fits the bill.  The biggest problem I have is needing to limit the number of rounds played, due to phyisical demands & time constraints.  Most of the schedules I have seen, require 11 rounds to be played, which will ensure that all 12 players play with each other once & play against everyone else twice.  But due to the constraints above, I need to limit the number of matches to 5 or 6 (if possible).

So the rules I propose for this tournament are:
 - all players must play at least 1 match with or against every other player
 - a player can only play with another player once

What is the minimum number of rounds required to meet the above for a 12 player round robin?  

Would also be nice to work this out for a 8,9,10,11 person draw, including byes if necessary.  

[Ian Wakeling]

I think at least 6 rounds are necessary to satisfy your rules, which is also enough for everyone to oppose at least once.  For example

  (12  9 v  2  7)  (4 10 v  3  1)  (8  5 v 6 11)
  (10  7 v  3  8)  (5 11 v  1  2)  (9  6 v 4 12)
  (11  8 v  1  9)  (6 12 v  2  3)  (7  4 v 5 10)
  ( 8 10 v 12  2)  (4  6 v 11  7)  (3  9 v 5  1)
  ( 9 11 v 10  3)  (5  4 v 12  8)  (1  7 v 6  2)
  ( 7 12 v 11  1)  (6  5 v 10  9)  (2  8 v 4  3)

With 9 or 11 players things will get messy and you will not even be able to give everyone the same number of games.  With 8 players just drop a round or two from the 7 round whist schedule.  For 10 players it only makes sense to aim for 5 rounds so everyone gets exactly one bye, but then I don't believe it possible to meet your first rule.

Really there are no good schedules possible, so this is the reason your searches have drawn a blank.

[Lollylegs]

Thanks heaps Ian, that is exactly what I was looking for.  This problem has been a thorn in my side for a few years, as I used to run social tournaments at a tennis club, with very similar restrictions on the number of matches it's possible to play in a session.

The 12 player draw works best, as that is 3 tables fully utilised.  But unfortunately, we have to cater for as many people as turn up on the night, so I will need to have options for all the different numbers we might get (expecting 20-30 people, so a couple of different round robins will be run at the same time).  For the 10 person draw, I have managed to play around with your 12 person draw to knock out 2 players (I did it with player 1 & 11) & with a bit of shuffling to fill the gaps, I can do a fairly balanced 10 person draw, with 2 people having 2 byes & everyone else having 1 bye (just gotta work out how to score the bye).

I can use a standard whist draw for 8 players & maybe modify the game lengths, so they take the same amount of time as a 6 round draw. For the odd numbers, I might just make one of the players a bye, we often have stragglers, so if we get a latecomer, we can slot them in then.  But not much we can do if it works out uneven, we can only work with who we have turn up.

But anyways, thanks heaps, this has definitely helped me out greatly.

[Ian Wakeling]

The following is the best I can do for 10 players:

      game 1          game 2        byes
   (2  4 v 1 10) ( 9  7 v  6  5)   ( 8  3)
   (3  5 v 2  6) (10  8 v  7  1)   ( 9  4)
   (4  1 v 3  7) ( 6  9 v  8  2)   (10  5)
   (5  2 v 4  8) ( 7 10 v  9  3)   ( 6  1)
   (1  3 v 5  9) ( 8  6 v 10  4)   ( 7  2)

All the partnerships are different, all the opposition pairs are different, but there are 5 pairs of players who never partner or oppose (so your rule 1 is violated).  However these 5 pairs are the same as the bye pairs, so a good solution might be to have the byes play a singles game together.

Hope that helps.

[Lollylegs]

That will work great, I will use your suggestion of having them play singles.  

I now have reasonably well balanced draws for 8, 10 or 12 players.  Which will allow me to cater for whatever number of players turn up.  Only issue, I will have is that they will go for 5,6 or 7 rounds depending on what size draw is used & it is possible that all 3 sizes will be used on different tables on the one night.  So, I might need to adjust the match lengths to try & have all 3 finish at the same time.

Only pain point now will be if we have an odd number, in which case we may need to make one person a bye.  Although, this will really screw up the evenness of the draw.  I might just keep myself in reserve & only play if needed to make an even numbered draw.  I wasn't planning on playing, as running up to 3 round robins at the same time is going to be hectic enough.

Thanks again Ian, I'm really glad I stumbled upon this site/forum.