Sorry I went off half-cock on this one. Someone who knows how to use a machine could probably settle 12, 16 or even 20 players. For 8 players, although I badly misprinted it before, I still believe that three rounds are possible. Let me have one more go. round 1. Ab v. Bc Ca v. Dd round 2. Ac v. Cd Da v. Bb round 3. Ad v. Db Ba v. Cc Check? In rounds 123, A partners bcd and opposes cdb and BCD B cba bac ADC C adc dca DAB D dab abd CBA a CDB DBC dbc b ABD BDA cad c BAC ACB bda d DCA CAD acb -- each of the 10 columns contains 8 different letters, or am I still being stupid? R. On Fri, 23 Jan 2004, R. Hess wrote:
Dear Richard,
I wanted to thank you for giving some attention to my mixed doubles problem. It would have been nice to get a solution with 9 rounds as you attempted but I now wonder that it may be impossible. The case for 8 players only allows two rounds (when three would allow each man to play against the remaining three men). I also believe that three rounds is probably the limit for 12 players. Accordingly the limit for 20 players might be only 5 rounds (the best I can do so far). Thus any case that allows six or more rounds with 20 players would be progress.
All the best, Dick