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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.

Hauke Reddmann
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  • Those four guys must be pretty fun to play with... – David Jul 07 '21 at 10:03
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    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. https://en.wikipedia.org/wiki/List_of_world_records_in_chess#Highest_percentage_of_draws_in_a_tournament – L. Scott Johnson Jul 07 '21 at 13:31
  • If that happens it's decided on penalty kicks. – DJClayworth Jul 07 '21 at 14:36
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    @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...) – Hauke Reddmann Jul 08 '21 at 07:34
  • @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) – L. Scott Johnson Jul 09 '21 at 12:38
  • @L.ScottJohnson: Ah, wrong bracketing on the Google calculator :-) You are correct. Next time I use MATHEMATICA... – Hauke Reddmann Jul 09 '21 at 15:35

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According to the Wikipedia page of chess world records, 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.

L. Scott Johnson
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