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Odd number of teams for Swiss Tourney Bye or three-way?

#1 User is offline   Hanoi5 

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Posted 2010-October-22, 03:50

The setting is the following: 7 teams will be playing 5 rounds of a Swiss tournament. Each round will take 8 boards.

- Is it better a bye or a three-way table (for the bottom three)?
- How will the movement for the 3-table work? 4 boards against each? How is it scored? The other 2 teams are getting VP's from an 8-board chart, so how is that supposed to work?
- Should there be repetition of matches? If not for some rounds, at which point can teams play against each other again? There was a round robin previously so all the teams met before.

Thanks for your help.

 wyman, on 2012-May-04, 09:48, said:

Also, he rates to not have a heart void when he leads the 3.


 rbforster, on 2012-May-20, 21:04, said:

Besides playing for fun, most people also like to play bridge to win


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#2 User is offline   Gerardo 

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Posted 2010-October-22, 04:49

View PostHanoi5, on 2010-October-22, 03:50, said:

The setting is the following: 7 teams will be playing 5 rounds of a Swiss tournament. Each round will take 8 boards.


5 rounds are a lot. Ideally, # rounds ~ ceil(log2 # teams).
In the last round you'll have the first playing with the bottom, unless you allow replays (then it is Danish, not Swiss).

View PostHanoi5, on 2010-October-22, 03:50, said:

- Is it better a bye or a three-way table (for the bottom three)?
- How will the movement for the 3-table work? 4 boards against each? How is it scored? The other 2 teams are getting VP's from an 8-board chart, so how is that supposed to work?
- Should there be repetition of matches? If not for some rounds, at which point can teams play against each other again? There was a round robin previously so all the teams met before.

Thanks for your help.


I'd say 3-way, but not sure.
A 3-way takes 2 rounds, as each team faces 2 opponents.
Not sure how to score. I know you get an IMP diference for each team, my first instinct would be to VP that using same scale but 2x # boards, 16 in this case.
I think Danish allows last round replay only.

#3 User is offline   TimG 

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Posted 2010-October-22, 05:38

View PostHanoi5, on 2010-October-22, 03:50, said:

The setting is the following: 7 teams will be playing 5 rounds of a Swiss tournament. Each round will take 8 boards.

- Is it better a bye or a three-way table (for the bottom three)?
- How will the movement for the 3-table work? 4 boards against each? How is it scored? The other 2 teams are getting VP's from an 8-board chart, so how is that supposed to work?
- Should there be repetition of matches? If not for some rounds, at which point can teams play against each other again? There was a round robin previously so all the teams met before.

A three-way lasts two round so each match involves the same number of boards as a head-to-head match -- no need for any VP scaling.

As a participant, I'd much rather a three-way to a bye. Why sit out a round? Especially when not every team will get a bye.

What is the rationale behind the switch from round robin to Swiss? It seems to me much better to have a complete round robin rather than have each team miss a single other team.
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#4 User is offline   Hanoi5 

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Posted 2010-October-22, 05:56

View PostTimG, on 2010-October-22, 05:38, said:

What is the rationale behind the switch from round robin to Swiss? It seems to me much better to have a complete round robin rather than have each team miss a single other team.


Switch? There was no switch. The tournament was set for 4 Swiss sessions but with only 7 teams a complete round robin was done first and then the 5 Swiss rounds.

 wyman, on 2012-May-04, 09:48, said:

Also, he rates to not have a heart void when he leads the 3.


 rbforster, on 2012-May-20, 21:04, said:

Besides playing for fun, most people also like to play bridge to win


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#5 User is offline   TimG 

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Posted 2010-October-22, 06:01

View PostHanoi5, on 2010-October-22, 03:50, said:

There was a round robin previously so all the teams met before.



View PostTimG, on 2010-October-22, 05:38, said:

What is the rationale behind the switch from round robin to Swiss? It seems to me much better to have a complete round robin rather than have each team miss a single other team.



View PostHanoi5, on 2010-October-22, 05:56, said:

Switch? There was no switch. The tournament was set for 4 Swiss sessions but with only 7 teams a complete round robin was done first and then the 5 Swiss rounds.


Ahh, I read this to mean that in previous runnings of this event, the conditions of contest called for a round robin, not that in earlier stages of this event there had been a round robin.
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#6 User is offline   gnasher 

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Posted 2010-October-22, 06:26

With the scenario you describe, I would play a round robin with longer matches, or two round robins, or a round robin followed by knockout for the top two or four teams.

The usual reasons for playing a Swiss are:
- It's a reasonably fair way to produce a winner from a large number of teams
- It ensures that teams don't have to play many matches against teams that are markedly better or worse, thereby making the event more enjoyable for most.
Neither of these applies here, so there's no particular benefit to playing a Swiss. All it does is unfairly disadvantage the two teams who don't play the weakest team.

Regarding the original question of whether to have a three-way or a sit-out, I'm sure that most competitors would prefer to play than to sit out.
... that would still not be conclusive proof, before someone wants to explain that to me as well as if I was a 5 year-old. - gwnn
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#7 User is offline   Bbradley62 

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Posted 2010-October-22, 06:41

Definitely 3-way over bye.

How's this for an odd (but maybe the most fair) format? In each of the 4 sessions, play a Mitchell movement with each team playing 4 boards against each of the other 6 teams. At the end, you will have played a 16-board match against each of the other teams.

Edit: I guess it wouldn't quite be a Mitchell, but I'm sure you get the idea.
Re-edit: Each round, EW pairs move up one table; boards move down, skipping two tables.
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Posted 2010-October-22, 06:59

Stronlgly suggest you consider a round robin of 6 rounds at 6 or 7 boards instead of using a Swiss for this low numer of teams.
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#9 User is offline   Free 

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Posted 2010-October-22, 07:37

If you want to play the swiss, I'd definitely choose for the 3-table.

Put the teams in the following order (NS vs EW):
table 1: A vs B
table 2: B vs C
table 3: C vs A

Now let them all play the same 8 boards. The pairs will compare their scores with their teammates, and get a result on 8 boards.

Example scores for 1 deal:
1. A +100 (B -100)
2. B +100 (C -100)
3. C -50 (A +50)
This will give A +150 on this board, B 0, and C -150. Total points will always add up to 0.

Not sure where in the ranking you should use the 3-table. Perhaps the top teams should play this way, perhaps the middle, perhaps the bottom teams, no idea.
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#10 User is offline   Fluffy 

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Posted 2010-October-22, 17:04

View PostBbradley62, on 2010-October-22, 06:41, said:

Definitely 3-way over bye.

How's this for an odd (but maybe the most fair) format? In each of the 4 sessions, play a Mitchell movement with each team playing 4 boards against each of the other 6 teams. At the end, you will have played a 16-board match against each of the other teams.

Edit: I guess it wouldn't quite be a Mitchell, but I'm sure you get the idea.
Re-edit: Each round, EW pairs move up one table; boards move down, skipping two tables.

I think this only works for 5 teams

Not yet fully sure, but I think for 7 teams boards have to move down 3 tables, the movement seems to fit then, and IMO is the best solution, 24 boards per session and you play against everyone with no byes.
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#11 User is offline   Bbradley62 

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Posted 2010-October-22, 17:13

View PostFluffy, on 2010-October-22, 17:04, said:

I think this only works for 5 teams

Not yet fully sure, but I think for 7 teams boards have to move down 3 tables, the movement seems to fit then, and IMO is the best solution, 24 boards per session and you play against everyone with no byes.

"down, skipping two tables" and "down 3 tables" are the same thing. Works well for 7 teams.
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#12 User is offline   barmar 

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Posted 2010-October-22, 22:30

View PostTimG, on 2010-October-22, 05:38, said:

A three-way lasts two round so each match involves the same number of boards as a head-to-head match -- no need for any VP scaling.

But there are an odd number of rounds, so the last round has to be a 3-way with half as many boards against each team.

Played in a Swiss on Sunday with 7 rounds of 8 boards and an odd number of teams. Before the last round, the TD asked if a team was willing to volunteer to drop out (they would get a win for the last round, but no VPs), so he wouldn't have to do a one-round 3-way. I don't know if anyone took him up on it.

#13 User is offline   Free 

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Posted 2010-October-23, 00:10

View Postbarmar, on 2010-October-22, 22:30, said:

But there are an odd number of rounds, so the last round has to be a 3-way with half as many boards against each team.

Read my post! Please! So everyone can stop whining about half the number of boards...
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#14 User is offline   gordontd 

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Posted 2010-October-23, 02:29

View PostFree, on 2010-October-23, 00:10, said:

Read my post! Please! So everyone can stop whining about half the number of boards...

I've read it, but it doesn't make sense, because you are suggesting that we have different opponents from our team-mates. Shouting at us to read it doesn't make it meaningful.
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#15 User is offline   Fluffy 

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Posted 2010-October-23, 03:24

View PostBbradley62, on 2010-October-22, 17:13, said:

"down, skipping two tables" and "down 3 tables" are the same thing. Works well for 7 teams.

Ahh right sorry, I think your solution looks much better than anything proposed, If you have segment lenght problem you can just play 2, 3 or 4 boards whatever you want. This system is specially indicated for 5 teams where the bye is trully awful.
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Posted 2010-October-25, 08:52

View Postgordontd, on 2010-October-23, 02:29, said:

I've read it, but it doesn't make sense, because you are suggesting that we have different opponents from our team-mates. Shouting at us to read it doesn't make it meaningful.

So everyone ignores it because it feels weird, great. We've used this method to play with 3 teams a lot in the past and you get a representative result. If you don't want to use a simple and working solution where you get a result and nobody has to sit out, fine by me. If you want to explore some new grounds, continue reading.

Yes, you are playing against opponents from a different team, but so are the other 2 teams. In the end you don't need to modify the number of boards and you can compare 2 scores which resemble your own team's capabilities. Your team has played the NS and the EW hands. It doesn't matter if you play against 2 pairs of the same team or not. You compare the scores of your team, and calculate the imp difference. With that imp difference you calculate your own VPs (if you'd win 17-13, you just get 17). Eventually, you don't win/lose a 3-table match against 1 team, each team just gets it's own VP score. Moreover the average VP score usually will be 15 (unless one team gets beaten up like it would lose 25-0 for example).
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#17 User is offline   TylerE 

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Posted 2010-October-25, 11:02

The way it's around here, which seems fair to me, is as follows:

First 3-way: Random draw (last 3 teams numerically, random team #s)

Subsequent 3-ways: Bottom 3 teams in overall rankings

If playing an odd number of matches:
Before the last round, the very bottom team is awarded a tie, the other two bottom teams play a normal match.
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#18 User is offline   Gerben42 

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Posted 2010-October-25, 14:06

I suggest not to have a Swiss with the number of rounds more than half the number of teams. Just play a heptagon movement, if needed in two 24-board sessions. Letting a team sit out for 8 boards (1 hours) is not even worth discussing I think.

I.E. What Fluffy said :)
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#19 User is offline   gordontd 

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Posted 2010-October-26, 01:55

View PostFree, on 2010-October-25, 08:52, said:

If you don't want to use a simple and working solution where you get a result and nobody has to sit out, fine by me.
There already exists such a solution, routinely used. Your method does not seem to be an improvement on it.
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Posted 2010-October-26, 05:47

View Postgordontd, on 2010-October-26, 01:55, said:

There already exists such a solution, routinely used. Your method does not seem to be an improvement on it.

So why don't you explain it and help the OP instead of targetting someone's (in your eyes) inferior method? How will you let all people play at the same time without a sit out and without changing the number of boards?

Unless I'm missing something, this is theoretically impossible if you want pairs of one team to play only against pairs of one other team. This is also known as the pigeon whole principle.
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