Author: Peter Berger
Date: 05:35:04 06/09/04
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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 ;). > >It allows for the 4th round: > >E-A >C-B >F-D > >Uri
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