Author: Uri Blass
Date: 05:50:30 06/09/04
Go up one level in this thread
On June 09, 2004 at 08:35:04, Peter Berger wrote: >On June 09, 2004 at 08:16:49, Uri Blass wrote: > >>On June 09, 2004 at 05:36:44, Peter Berger wrote: >> >>>On June 09, 2004 at 03:54:25, Mark Winands wrote: >>> >>>>2. The tournament will be an 11-round Swiss-system event, using standard >>>>(non-accelerated) Swiss pairings. The provisional playing schedule was given on >>>>page 293 of the December issue. >>> >>>In case there were only 13 participants I wonder if it would really be possible >>>to do legal Swiss pairings for 11 rounds - probably not. >>> >>>Someone sent me an interesting thought experiment some time ago. >>> >>>Assume a Swiss event with six players, A-F - A is the highest seed. >>> >>>1st round: >>> >>>A-D 1-0 >>>E-B 0-1 >>>C-F 0-1 >>> >>>2nd round: >>> >>>A is paired first, F gets downfloat and has already played C, thus: >>> >>>B-A 1/2 >>>F-E 1/2 >>>D-C 1/2 >>> >>>Standings: >>> >>>A:1.5 (WB) >>>B:1.5 (BW) >>>F:1.5 (BW,d) >>>C:0.5 (WB) >>>D:0.5 (BW) >>>E:0.5 (WB,u) >>> >>>F already had downfloat, so it's B's turn. A gets F, B gets C, so: >>> >>>3rd round: >>> >>>A-F >>>C-B >>>E-D >>> >>>Whatever the results of the 3 round now, there are no legal pairings for round >>>4. >>> >>>It is possible that there is some mistake in the above, but I don't think the >>>principal problem can be avoided. >>> >>>Peter >>It means that >>A-F >>C-B >>E-D >> >>is illegal pairing after >> >>A-D >>E-B >>C-F >> >>B-A >>F-E >>D-C >> >>I expect every intelligent program that calculates pairing not to do that >>pairing. >> >>What is bad about the following pairing for the 3th round? >>B-F >>A-C >>D-E > >It isn't the pairing that you will get if you follow the FIDE rules, that's the >only problem. > >Peter > >PS: The rules are very complicated so it's possible that I miss something. A >FIDE arbiter would be helpful ;). I think that the first rule should be to allow possible pairing for all the rounds. You can define priorities between possibilities that allow pairing for all the rounds but allow pairing for all the rounds seems to me logical and it seems to me logical that every program that gives a pairing should check that there are possible pairing for all the rounds later and to cancel the pairing as illegal if there is not legal pairing for the next rounds. Uri
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