Of course there are disadvantageous sides in Sos. This thread's example tournament was one good example. But I would say that there are great many good things because there are dozens of examples where SOS has worked well and given us justified winner without spending extra day with playoffs. Of course it would be good thing to increase rounds instead of breaking ties, but this is not always possible or desired.

One thing to note, that it is also possible that we have clear winner after five rounds but after round 6 situation is even again. In this case MMS or Swiss score was bad tiebreaker and gave us wrong winner.

I am not very big fan of playoffs if they are not best of three matches. One individual game should not decide too much.

SOS has given us dozens of winners many people felt uneasy with but did not complain about publicly - but read kibitz and listen what people said about EGC results during the last years. At least it was my impression that what is a satisfying result for the tie breaking specialist not necessarily is satisfying for the public.

How a play-off between tied players can be worse than a one-point difference in MMS / Swiss score remains your secret, you lost me there. I mean honestly you really would prefer a mere SOS point (= the result of a single game but one played by other players than the tied ones) over a play-off (= the result of single game but between the players with even performance up to that point) as a tie breaker?

Sure, but it doesn't decide too much. It tiebreaks based on the fact that the players had the same record over a number of games already played. The purpose of using them is that the tournament system has decided the players are basically on a knife-edge having each played a number of competitive games, and just needs something to pick one over the other. If a player didn't want to lose on tiebreaks, he could have got a perfect record in the main tournament and not had to go there.

I think tapir's solution is ideal in all situations where timing and schedule would allow it.

I don't think you can organise a tournament where you have a certainty that you never will have floaters.
If it was a tournament of 10 people there whould be a floater after round 1 (just because 10/2 is an odd number)

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Example: some people have suggested to play 9 round main tournament, and if standigs are not clear, then 10th round.

In EGC 2009 Eunkuk was in 8 wins alone after round 9. If tournament had been terminated here, Eunkuk would have been the clear winner. However after 10th round it was again even and not so clear, so it would have been bad thing to terminate tournament before round 10. Therefore as long as there are not played full round robins, McMahon and Swiss does give only approximation of the winner. Therefore Swiss score or MMS is not reliable indication who has done best. However we can make it more reliable indicator by increasing round count and allowing top players to meet twice.

McMahon's idea is to increase effective rounds by reducing the size of the top group. Therefore McMahon can give more reliable winner than Swiss. Idea with McMahon is to select top group so that distribution of ratings is moderate in the top group so that first round is not wasted due to too big skill difference.



This is not very often the case, but schedule is often limiting factor, if we do not wan't to break ties by blitz games, what is of course an option.

But in my opinion, if we want to have playoffs, then we play double elimination tournament in the first place. But this is not what I want to do, because go tournaments are not events where all that matters is to find winner, but events where all that matters is to find who is 42nd player in the tournament. I.e. Finding winner is not the point, but good tournament for every participant.

However I did suggest that there is separate play-offs between top two Europeans in later date, but in general this idea was not well received. And perhaps it is good thing, because we do not want to tier down current format of EGC, because European Championship's prize money depends heavily on the number of participants.

Hi all,

I was responsible for the pairings during the EWGC, and read your remarks with a lot of interest. I agree that round 1 was kind of "wasted" (at least for the purpose of ranking people, but maybe not for the weaker girls, who had the opportunity to play the best players), I am not completely convinced that an accelerated pairing, such as described above, would have made the final ranking more accurate.

I did some simulations with opengotha to see how the accelerated pairing (let's call it AP) would behave. Here are my remarks :

1. With the AP, the top players eliminate themselves during the first 2 rounds. So we get very interesting games during the first 2 rounds. However round 3 of AP looks like round 1 of the original pairing (OP), with a lot of very uneven games.

2. It appears that the counter performances of Natalia (5D) against Alison (1D), and Elvina (3D) against Dominique (1K), the performance of Natalia against Pei (6D) make it difficult to obtain a satisfying ranking. The AP doesn't solve this problem. By the way, for this particular tournament, we needed to establish a clear ranking of 3 or 4 top players, and not just a winner, in case the winner can't go to Japan. The AP is very bad at doing this.

I think that it is simply impossible to rank 20 players in 5 rounds without deciding from the beginning that some players will not have any chance of winning the tournament. But choosing who is in the top group can be problematic as well.

AP really only works well if the number of players is a multiple of 8, and then only if the group is large enough. I think you'll need at least 32 players to make it work well.

With a group of 20 players, to decide a winner in 5 rounds, I think only knock-out works. Have the weakest 8 play one round, then add the 12 strongest players to the 4 winners for a 4 round 16 player knock-out. You can add a 3rd/4th place match between the losing semi-finalists if you need more places (though the accuracy of KO is limited for that).

Players that are knocked out can be paired amongst themselves if you want to give them the opportunity to play more games.

Liisa, I find it a bit hard to argue the way you rearrange sentences and deflect arguments. This is especially strange if you answer the proposal of play-offs in case of tied players with a discussion of the merits of double elimination, which is an altogether different tournament format. So, you say that a tournament format (McMahon + play-off as tie breaker) which gives the 42nd a lot of exciting games and a placement as exact as McMahon can, is actually meant to be a format which leaves him out of competition after two lost games and without any meaningful placement (double elimination). And since A (basically =) B, you oppose A because B is not a vowel.

Schedules will never allow for play-offs unless they are scheduled beforehand. That is if tournament directors reserve a time slot for a possible play-off - maybe parallel to a side activity which the tied players may afford to not participate in. I am quite sure that there is that much time in EGC or WAGC, but it may not be possible in a 7-round two-day tournament. Of course there are problems with play-offs when 3 or 5 players are tied and you will have to treat players of the same MMS differently, but that it is meant to be double elimination is not one of them.

tapir, If we have option to reserve time for play-offs, then we can play one extra round with regular McMahon. It is always more productive to play extra rounds, especially if top players are allowed to meet twice, than to play play-offs. If play-offs are not played with blitz time settings, e.g. 8 4 Fischer.

Sorry for may late responce.

The problem with accelerated pairings is that it does gamble that the initially higher placed players will win against the lower placed players.

If the initially lower placed players win against the higher placed players then the result with Accelerated pairings is worse than normal swiss pairing.

But also maybe playing against much weaker players does influence on how you do play in the next round. (don't you start with the idea that my opponent in this round is not much better than the opponent i just played)



We were there allready the winner was paired against a 3k in the first round (and number 2 against a 6k)

on http://www.chesscafe.com/geurt/geurt.htm (especially http://www.chesscafe.com/text/geurt125.pdf )
i found the (rough and ready) formula that you need (P + 7 x Q)/5 rounds to decide on Q places.

Following this formula you need at least 7 rounds to have a clear 1 2nd and 3rd place if you have 20 players.

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tapir, for some world champion results and effects of SOS on top players, see

http://groups.google.com/group/rec.game ... ode=source

http://groups.google.com/group/rec.game ... ode=source

For many years, I have criticised the low quality of SOS especially in 5 rounds Swiss or McMahon tournaments. This could be observed in many national or European weekend tournaments in ordinary, EGF or EGC events. SOS can at best show only what has happened but, in such low number rounds tournaments, the final top wins players have often played only too few games among each other, especially when there are relatively many (strong) participants or a too great initial top group in relation to a (by far) too small number of rounds. Even with perfect pairings, SOS can never in general solve a fundamentally flawed combination of tournament system and round number.

Better pairing strategies can reduce only the symptoms. Women championships have a great variety of player strengths. Therefore it is even far from obvious what could constitute a good pairing strategy in early rounds. Each of the following reference parameter is doubtful for such national or European women championships: rating, rank, earlier tournament performance, earlier values of other same-nation players. Doubtful because a too great fraction of participants have played too few recent tournament games or because same-nation players are too different in strength, too.

There is some good news though: For the European (Open) Champions, the EGF Rules Commission is suggesting (and I hope it will be adopted) for the currently revised EGC rules draft recommended pairing strategies (subject to the pairing programs' capabilities): Cross Pairing by rating (#1-#3, #2-#4) in rounds 1 and 2; Fold Pairing by MMS - SOS (#1-#4, #2-#3) in all later rounds. Thereby Alexander's 3d opponents will be history of the past (unless he loses his early rounds, of course). In the German Championship Preliminaries (6 rounds Swiss, SOS tiebreaker, player field 3d-6d, to qualify previously 6 or now 4 players), we have had very good experience with almost this pairing strategy combination. It does not fix SOS nor a constant round number, but given both it pairs pretty much as well as possible.

Can you publish the complete proposel (so we can all comment on it )

I think cross or slide pairing is better than fold pairing in the first rounds

But also that accelerated pairings would be even better

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There is no good reason to ever use accelerated pairings in a McMahon tournament.

That is true but many tournaments are not McMahon (for example the one we are discussing here )

also it the topgroup of a McMahon tournament is big accelerated pairing is a good idea for this group.

The main disadvantage of a McMahon tournament is that players outside the topgroup by definition are prohibited from winning the title.
With accelerated pairing they have (at least) a (theoretical) chance

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Robert's post referred to the EGC, which is McMahon.



No, if the top group is too big, it should be made smaller. In any situation where the top group is sufficiently large and has sufficiently large differences in skill that AP can be argued for, the same arguments can be used to support making the top group smaller, which is then the better solution.



No, they are not. If a player at the EGC starts outside the top group and scores 10/10, he will very probably win the tournament (only way to lose would be a if a top group player had 9/10 and better SOS).

I've seen it happen in an actual tournament that a player from just outside the top group scored 5/5 and shared first place with a 4/5 top group player (the prize money was shared equally between them).

willemien, the current draft is being consulted by the EGF Committee. Therefore the timing for your request is unsuitable. I can state the prior Rules Commission's major intentions though:

- The text "Fill any remaining places with Europeans according to the EGF rating list." shall be deleted so that, in case of too few strong non-Europeans etc., a supergroup has 24+ instead of up to ca. 32 Europeans.
- Recommended Cross Pairing for McMahon rounds 1 + 2, Fold Pairing for later rounds.
- On the second Wednesday, i.e., after round 7 and before the new KO for the EC title, relegation games can occur as follows: 1) Number the top 16 Europeans by MMS-SOS-rating-lottery. 2) Fold Compare them. 3) Of each compared pair, seed the player with greater MMS and send back the other player to the main T. 4) Compared pairs with equal MMS play a relegation game; winner qualifies for KO, loser rejoins the main T.
- Minimize repeated pairings.
- KO has also 3rd place game.
- Losers of relegation and KO quarter finals play all remaining main T rounds (to give non-Europeans enough interesting opponents).
- Only non-Europeans can become EuOpenCh and only if they are in top MMS group after round 10.
- Details for main T final tiebreakers.

I disagree with you here, is not better to have a lot of discussion about it?
(Or should we all join the rules comitee?)


t



what do you mean here?
you take the top 16 european players in the tournament, (not just the top 8)

you compare 1-16 2-15 3-14 4-13 5-12 6-11 7-10 and 8-9(this is fold comparing)

and then take the better in each pair?
(why not take just the top 8 straigt away?)



This differs from what you said in the rules forum (but that was not related to this here off course )



In the last EGC for the first time an european won the open title, and now we make it impossible. (that is no good publicity)

correction in the fold comparing (sorry there was a mistake)

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You don't want to discuss all the linguistic typos anyway.



You got it, except for a typo of omitting #4 and the ensuing typos.



Yes, IF there is a better one by MMS.

Here are some samples:

The first row of every block of two rows denotes how many wins less than player #1 the players have.

+ = qualified automatically
X = winner of same letter pairing qualifies
- = not qualified automatically



Cases with some 3s instead of 2s would look similar.



For these reasons:
- With the Fold Comparison and the possible relegation games, each seeded player has won at least one game more than each not seeded player. This is a very good seeding criterion!
- EDIT: It becomes much less likely that players with 2 wins less than the top seeded Europeans could qualify. :EDIT
- SOS as seeding criterion would be much worse than depending only on greater numbers of wins (aka greater MMS).
- SOS would invite easy cheating as allegedly happended similarly in the EGC 1987 when same-nation players were strongly suspected to have lost intentionally against other-nation competitors for the title.



Feel the joy of seeing the best possible criterion (greater wins / MMS) to be meaningfully and exclusively used at the decisive seeding in Europe's most important tournament!



I am not exactly sure what you refer to.



Would you prefer the 5th strongest European to get the Open title while Europeans 2 to 4 do not get a title?

That the Open title does not make much sense for a European holder any longer is a drawback of the last AGM's decision to invent the European KO finals while keeping the schedule pretty much unchanged.

Hm, maybe there is an alternative: The KO game results need to be copied into the McMahon anyway for the opponents' SOS values. So one might allow the top European in the McMahon to get the Open title. - IMO, such does not make much sense, either: The separation of the top 4 Europeans is too great to compare their own final SOS meaningfully with the top non-Europeans' SOS.

So the sheer honour (eh, and prize money) of a European being placed above the non-European Open EC must be good enough a reward.

I agre e lets bnot do that



I don't understand this (Or do i try not to understand this)
you introduce here an extra round to decide who of the A B C and sometimes D goes to the final KO rounds?

But also there is a problem with the sorting allready.

How do you sort the players even before you decide who is welcome to this (extra qualification round)
If you introduce an extra round anyway there are possibly better ways. (let every european join with just enough wins)




For these reasons:
- With the Fold Comparison and the possible relegation games, each seeded player has won at least one game more than each not seeded player. This is a very good seeding criterion!
- EDIT: It becomes much less likely that players with 2 wins less than the top seeded Europeans could qualify. :EDIT
- SOS as seeding criterion would be much worse than depending only on greater numbers of wins (aka greater MMS).
- SOS would invite easy cheating as allegedly happended similarly in the EGC 1987 when same-nation players were strongly suspected to have lost intentionally against other-nation competitors for the title.



Feel the joy of seeing the best possible criterion (greater wins / MMS) to be meaningfully and exclusively used at the decisive seeding in Europe's most important tournament!
[/quote]

If only i saw it that way

BTW i guess you mean by seeded the players who are in the top 8?



This one : viewtopic.php?f=45&t=2410



I hope the champion will see it that way. But you see the problem.

Maybe it is an idea to leave the decision to decide who is the Strongest European (professional) go-player to the European Go Professionals and only bother on the congress about the open Champion (who may also be an european)

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