Author: Ricardo Gibert
Date: 16:57:19 12/14/03
Go up one level in this thread
On December 14, 2003 at 12:39:34, David Dahlem wrote: >On December 14, 2003 at 05:29:04, George Tsavdaris wrote: > >>On December 13, 2003 at 22:56:28, Robert Hyatt wrote: >> >>>On December 13, 2003 at 21:09:13, David Dahlem wrote: >>> >>>>Is there a formula to calculate the number of rounds in Swiss tournaments with >>>>various number of participants so as to optimize the odds for a clear winner? >>>> >>>>Regards >>>>Dave >>> >>> >>>log2(#players) rounded up to next whole number. If you want a more accurate >>>2-3 place, add another round. >> >>I don't understand. This means that for 20 participants the number of round >>must be Log2(20)= 4.32 ---> 5. Too little rounds i think. > >I don't understand this formula either. For example, the latest WCCC Tourney at >Graz had 16 participants, and 11 rounds were played. How do tournament directors >decide how many rounds will be played? > >Regards >Dave You should probably be interpreting this formula as a minimum. People like more rounds to make the result seem less random. In Graz, the tournament would have been better if it had been played as a double round swiss. Ten rounds with 2 games played played between the same programs instead of just one instead, but for some reason this type of idea is not popular. What they did instead wound up having rather silly pairings towards the of the tournament with the contestants at the top of the crosstable being paired against the those near the bottom. This is not considered desirable, though it does have the desirable effect of compelling the top contenders to play for a decisive result in the last round. Actually there is no "formula." The formula above is ripped off from the one for knockout tournaments where all the games are decisive. In chess, you have draws and a swiss is not the same as a knockout tournament. In fact, swiss tournaments use a number of different pairing systems, so no single formula is "best." In practice in human tournaments, a typical prize structure often militates against the tournaments leaders seeking a decisive result in the last round. Accepting a tied result is usually preferable leaving the relative rankings among the top contenders unchanged. Call it "mutual fear" if you like, but actually the money odds are dictating the drawn result. This makes the last round often _seem_ redundant and avoiding a tied result difficult. BTW, this does not seem to be a problem in computer events. Actually, by the way you phrased your question, the number of rounds that should be played to "...optimize the odds for a clear winner," should be _infinity_. Obviously that isn't helpful at all. Enough said. If you want to insist on having a formula, then I would suggest the same formula with a slight modification. Add one extra round. This would ameliorate the chances of tied result due to "mutual fear" in the last round. In any case, any such formula should be taken with a grain of salt.
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