Round Robin Tournament Scheduling

Recent Posts

Requests / Epic Question
« Last post by robert.keller on July 08, 2020, 11:05:47 AM »
So.  I would like to create an excel file that allows me to create rotational groups of people with no repeat but I would also like the ability to edit the first few groupings.  For example.  If one week I have 20 people and I want them to all meet one on one but not see the same person twice, while also being able to edit the first few groupings of people so if there are specific people that I would like to meet they can.  So its kind of like creating a rotational schedule that is not random and does not repeat which is also editable for the first few groupings.  

Thank you for any help provided!
Requests / Re: HELP!!
« Last post by Ian Wakeling on July 07, 2020, 03:27:37 AM »
I think it is impossible to have a schedule with the properties that you are asking for, so you must compromise here.  The closest schedule that I know is this one.  However everyone participates fully and has one same gender player who is opposed twice.  You could remove F1 and M6 from the two games in which they participate and replace them with players who have a bye in that round, but this will leave the schedule quite unbalanced, with some players having one game more than others.
Requests / HELP!!
« Last post by vballgirl on July 06, 2020, 04:20:15 PM »
Hello all,

I am having trouble trying to format a tournament.  We will only have 2 courts running at a time, so a maximum of 8 players can play.  We have 6 females and 6 males.  We are trying to create mixed teams of 2 (one female and one male).  Due to time constraints, we know that we will have one female not play with nor against another male.  For example, F1 will never play against or with M6.  Our goal is to have each female and male play with each other and against each other once (except for that one opposite gender person that you will not play with or against).  Help please!
Mathematics / Re: Partial Schedule Played, complete it
« Last post by Ian Wakeling on July 06, 2020, 08:29:54 AM »
Thanks for posting your algorithm.  I don't have any specific literature to point to, but I know that the operations research people (I am not one of them) have studied these sorts of sports scheduling problems.  Common methods for finding solutions are constraint programming, integer programming and perhaps genetic algorithms.

It seems that your approach is working well, and I think this is because the random element prevents it becoming trapped at local optima.  There is probably an alternative approach where the matches are first fixed, and then the non-locked ones are moved around the schedule with the aim of having no repeated teams in a round.
Mathematics / Partial Schedule Played, complete it
« Last post by Rourke on July 02, 2020, 08:49:29 PM »
Just stumbled on this board, thanks for putting it together! I've always had an interest in tournament scheduling, and have been able to put it into practice several times.

We've had a situation in our national league where due to coronavirus a big slab of the season went missing after a few rounds had been played. The original schedule was not a perfect double round-robin. The organisers want to complete it with a single round-robin, given the shortened time. They also have a few key matches that must be played on a certain date (Locked).

I managed to develop an algorithm that seems to work, something like simulated annealing. Sharing it here for feedback, and to see if anyone can point me to similar published work:

  • For each remaining round, generate a random permutation of the teams that are not involved in a Locked match, and put them in pairs of teams
  • Count how many times each team plays each other in the full fixture
  • While there are team pair counts that are zero:
    • Randomly choose a pair A:B with count more than one (overplayed)
    • Randomly choose one of their non-Locked matches
    • Find another overplayed match in the same round; if there are none, choose any match X:Y in the round
    • Decide whether A:X & B:Y or A:Y & B:X would be the better replacement by testing the overplayed count; if equal, flip a coin
    • Make the swap
    • Update the team pair counts
This seems to steadily move the overplayed count down, with random walks where it gets larger for a while. I'm yet to see it fail, but that would assuredly happen if enough of the fixture was already Locked.

It also works if you want to allow byes, just by adding an extra round, running the algorithm, then removing some of the overplayed matches at the end.

You can then balance the home & away counts with a similar stochastic process.

Requests / Re: Beer olympics
« Last post by Ian Wakeling on July 02, 2020, 08:43:40 AM »
There would have to be 28 rounds in order for every team to play each other at all games - that does sound too much. For anything smaller you need to decide between having every team play each game the same number of times (any multiple of 4 rounds), and having every team play every other team the same number of times (any multiple of 7 rounds).  The following schedule gives you two possibilites.

  Game1 Game2 Game3 Game4
R1 (3 8) (1 2) (4 7) (5 6)
R2 (6 7) (4 2) (5 8) (1 3)
R3 (6 2) (5 3) (1 4) (7 8)
R4 (1 5) (6 4) (7 3) (8 2)
R5 (8 4) (7 5) (1 6) (2 3)
R6 (3 4) (8 6) (2 5) (1 7)
R7 (2 7) (1 8) (3 6) (4 5)
R8 (1 5) (3 7) (2 8) (4 6)

play rounds 1 to 7 to have every team play each other once, or play all 8 rounds to have each team play each game twice.
Comments and Thanks / MOVED: Beer olympics
« Last post by Ian Wakeling on July 02, 2020, 08:30:50 AM »
Requests / Beer olympics
« Last post by ssingler on July 02, 2020, 12:22:21 AM »
Were doing a beer olympics this weekend and we have 8 teams with 4 different games. Trying to find the best way to make a bracket for this. Would like to have everyone play every game against each other but that seems a bit much. But also want to make it fair to all teams. Any suggestions are greatly appreciated.  
That's weird.   I just tried myself and I get the zipped Excel file (xlsm) as intended.  If you would like to click on the envelope icon under my name and then send me an e-mail, then I can reply with the Excel file attached.
I am trying to download the spreadsheet that was paperclipped but it downloads as a Word file.  Any thoughts on how to get this file correctly as I assume it is an Excel file (I have excel on my computer), so not sure what is going wrong.  Thanks!