# All draw Round Robin

Do you know a chess tournament (I wrote Round Robin, since it seems extremely improbable for Swiss) where all games ended drawn? Since of course even I can come up from personal experience with a four player tournament where this happened, let's assume at least 8 players. Calculating with a fairly valid drawing probability of 1/2, I get 1/2^(8*7/2)~10^-9, so this would be a very rare event.

• Those four guys must be pretty fun to play with... Commented Jul 7, 2021 at 10:03
• The record for draw percentage is 93.3 (that tournament had ten players), meaning no: there hasn't been a recorded tournament with 100% draws. en.wikipedia.org/wiki/… Commented Jul 7, 2021 at 13:31
• If that happens it's decided on penalty kicks. Commented Jul 7, 2021 at 14:36
• @L.ScottJohnson: Can you upgrade that to an answer? I didn't know that there was a chess record page on Wiki!! BTW, that result has p=10^-24...(Note that the page probably only records from some certain ELO level upwards, so I won't exclude it has happened at the Hicksville town championship...) Commented Jul 8, 2021 at 7:34
• @HaukeReddmann with a draw probability of 50%, I calculate drawing 42 of 45 games has p~=10^-10. `C(45,42) * 0.5^42 * (1 - 0.5)^(45-42) = 4.033e-10` . (For "42 or more") the odds go up slightly: 4.328e-10) Commented Jul 9, 2021 at 12:38