EWGC-2010

[tapir]

Basically, you (Liisa) say it was not random, but it was an award to the player with the highest previous rating of some SOS points for free. Is that any better? And at least WAGC/KPMC do not fix the first round to avoid top players being paired against random 1-3 dans in the first round, because they regularly were in the last years e.g. China vs. South Africa (when Victor Chow isn't representative), Korea vs. Lithuania.

And of course even if you pair two top-WAGC players against a 2d with identical GoR in the first round it is somehow random whether this one ends with 3 or 4 wins and both can be trusted to be able to win a game against any other 2d as well.

Bottom line: This time we had 3 or 5 SOS points difference (Vanessa or Rita resp.) and we consider that result unsatisfactory but we are still ready to decide EGC or WAGC victory on a single SOS point. I would have a hard time to explain this to my fellow go players.

Indeed three point difference is here far less convincing than it normally should be. If you examine closer the pairing first round was arranged by GoR as it should arrange in regular Swiss. Random is always bad option in first round because it can give huge benefit or handicap just by good or bad luck. Therefore naturally Pei got strongest opponent in the first round of top half players.

[willemien]

A glance at the result table shows that there is no accuracy to talk about. There is a two point difference (SOS) between first and second placed just by the truly random first game and later on this difference did increase, even though the second did not lose a game (until the last round). So yes, the first one played a harder tournament (SOS rationale), but 2nd to 5th did not get a chance to play it. Which is in a way a feature, if you lose in the second round, but obviously it is a flaw if you have straight wins. So we got the opportunity to see a 3 point SOS-difference which still does not look convincing.

Indeed three point difference is here far less convincing than it normally should be. If you examine closer the pairing first round was arranged by GoR as it should arrange in regular Swiss. Random is always bad option in first round because it can give huge benefit or handicap just by good or bad luck. Therefore naturally Pei got strongest opponent in the first round of top half players.

Second issue was that Rita was paired downwards on third round. This gave her intolerable disadvantage.

I you need to pair somebody down, and who should be chosen?
Bexfield Alison allready had a SOS disadvantage
Kalsberg Elvina had allready played two weak players
So i think it is a reasonable choice

Third issue was that Pei was paired manually constantly against other top players. This gave Pei huge advantage in winning competition. Three point difference in SOS should not be possible in regularly paired tournament.

She had more the luck that her opponents played well, it doesn't look that she was constantly paired against other top players

And fourth Natalja lost on second round, but this should not exclude her away from winning competition. This is the reason why 20 players is over sized group size with this distribution of ratings.

After round 2 Natalja had a SOS advantage (compared against the others with one win)
i guess therefor she was paired down.

I wait for the day when a WAGC is decided by whether the winner was paired against a 5k or a 2d in the first round, maybe some people will then realize that there is something wrong with the system.

In swiss pairing it is just plain wrong to use random in the first round, because of this reason.

If they had used accelerated pairing the first round would also not have been played,
In round 1
1 to 5 would play 6-10 and
11- 15 would have played 16-20

But if you allready only have such a small tournament as here splitting it up in two groups (a topgroup and the rest) is hardly a option either

I do not see point here. I stated that maximum size is 12-14 imo, but minimum is 6-8 for top group. But this depends heavily on rating distribution. In this particular tournament I would choose 10 players into top group (1k+) and for the rest regular McMahon tournament with MMS-1 handicaps.

Then the offical contesder of Switzerland had not even a formal chance to win the tournament

[quote]
Idea is that in this case first round was wasted, because smallest GoR difference was more than 800 points between pairs. I would say that minimum difference between pairs should not be much bigger than 300 points in the first round.


The Aspergus now works fine
nice to be able to see how it was after just a couple of rounds.

[Liisa]

Bottom line: This time we had 3 or 5 SOS points difference (Vanessa or Rita resp.) and we consider that result unsatisfactory but we are still ready to decide EGC or WAGC victory on a single SOS point. I would have a hard time to explain this to my fellow go players.

In the case of EGC it is usually clear, because there are plenty of rounds to make soses even by folding. E.g. although it was little dubious to pair Cornel and Alexandr in the first round, it still was not hopeless situation for Alexandr to fight for the championship in spite of defeat in the first round, because there was plenty of rounds left.

Same goes for WAGC because there is 8 rounds to even out SOS'es, but certainly it is not guaranteed. But with 5 rounds it is completely different case. And if we want to be sure that there are no problems who is the winner, pairing must be designed carefully. If McMahon pairing is done well, then there should not be problems with SOS as a tiebreaker even in 5 round tournament, but this is not guaranteed.

I you need to pair somebody down, and who should be chosen?... So i think it is a reasonable choice

This situation should have been prevented beforehand. This is the point. It is of course clear that if you have 20 players then you will end up serious ethical problems on round 3, and in practice you must choose someone who is paired out from championship competition.

[tapir]

Bottom line: This time we had 3 or 5 SOS points difference (Vanessa or Rita resp.) and we consider that result unsatisfactory but we are still ready to decide EGC or WAGC victory on a single SOS point. I would have a hard time to explain this to my fellow go players.

In the case of EGC it is usually clear, because there are plenty of rounds to make soses even by folding. E.g. although it was little dubious to pair Cornel and Alexandr in the first round, it still was not hopeless situation for Alexandr to fight for the championship in spite of defeat in the first round, because there was plenty of rounds left.

Same goes for WAGC because there is 8 rounds to even out SOS'es, but certainly it is not guaranteed. But with 5 rounds it is completely different case. And if we want to be sure that there are no problems who is the winner, pairing must be designed carefully. If McMahon pairing is done well, then there should not be problems with SOS as a tiebreaker even in 5 round tournament, but this is not guaranteed.

In the WAGC the top players have probably 4-5 sure wins and 3-4 contested games. Whether their opponents in the sure win games are finishing with 3,4 or 5 wins in the end is absolutely meaningless regarding the playing strength of the top players but it will break ties. And I do not belief there is a technical fix for this problem. Like changing pairing a bit here, using SOS-1 instead of SOS... I mean a 1 dan player not able to handle his clock or drinking too much on the last evening or forfeiting his game by arriving too late at the playing hall can decide the outcome of the WAGC because this changes SOS points of the top players. It is a sure call that something like this will happen one day, anyone going to bet against me on that?

And it probably did happen already for 3rd and 4th places, just nobody cares about that. E.g. last year Bertan Bilen 2d lost to John Gibson 2k by forfeit = arriving too late, both are far from contending for the championship still this has an effect at the top of the table, it retrospectively granted the Taiwanese player who played Gibson in the 2nd round an additional SOS-point changing his placement from shared 3-way 7th to shared 2-way 6th. And this is just one example I remembered from the last WAGC.

Reserving a day for play-offs to decide the winner - at least in long tournaments like EGC or WAGC - would be a better solution in my humble opinion.

[willemien]

I think with any tournament setup there will be problems for the lower finalists.
If somebody wins all her games it is easy (as long as there are less than 2^r, contestands) but for 2nd 3rd and further places discussion is possible.
and if nobody wins all her games, the problem is also about the winner

[Liisa]

Reserving a day for play-offs to decide the winner - at least in long tournaments like EGC or WAGC - would be a better solution in my humble opinion.

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.

[tapir]

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?

[topazg]

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

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.

[willemien]

I you need to pair somebody down, and who should be chosen?... So i think it is a reasonable choice

This situation should have been prevented beforehand. This is the point. It is of course clear that if you have 20 players then you will end up serious ethical problems on round 3, and in practice you must choose someone who is paired out from championship competition.

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)

[Liisa]

..one-point difference in MMS / Swiss score remains your secret, you lost me there.

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.

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

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.

[Remi]

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.

[HermanHiddema]

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.

[tapir]

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.

[Liisa]

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.

[willemien]

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)

I wait for the day when a WAGC is decided by whether the winner was paired against a 5k or a 2d in the first round, maybe some people will then realize that there is something wrong with the system.

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.