DOUBLE KNOCK OUT FORMAT

[MBV53]

HELLO MY CO-TDS!

WILL YOU PLEASE EXPLAIN ME ABOUT 23 TEAMS DOUBLE KNOCK OUT FORMAT?THE TEAM KNOCKED OUT WHEN IT LOOSES TWO MATCHES.

MBV

[gwnn]

I have been trying to cook up something but all I managed is a little unfair to at least some of the teams. But here is something for 24 teams: You really should get 24 teams.

 

Make 8 groups of three teams each. The winners go through to the main knockout, the losers to the consolation knockout.

 

The main knockout is classic. It will happen like:

 

16, 8, 4 teams after two rounds in the consolation

 

After the quarterfinals, 4 teams in the main knockout, 4 additional teams in the consolation.

 

8, 4, 2 after two rounds in the consolation.

 

After the semifinals, 2 teams still in the main knockout, 2 more teams in the consolation.

 

4, 2, 1 after two rounds in the consolation. We have a winner of the consolation.

 

After the final, 1 more team in the main knockout, they won it.

 

The loser of the final gets to play against the winner in the consolation final. He is the second winner.

 

Now you either let the winner of the main bracket play against the second winner, or not.

[gwnn]

Let's say you have 8 groups named A, B, C, D, E, F, G, H. You have

A1: winner of group A

A2: second in group A

A3: third in group A

and so on.

 

Then it would look like:

 

MAIN KO:

1. A1-B1

2. C1-D1

3. E1-F1

4. G1-H1

5. W1-W2 (winner of 1 vs winner of 2)

6. W3-W4

7. W5-W6

W7 is the winner of the main KO.

 

CONSOLATION KO:

8. A2-B3

9. C2-D3

10. E2-F3

11. G2-H3

12. A3-B2

13. C3-D2

14. E3-F2

15. G3-H2

16. W8-W9

16. W10-W11

16. W12-W13

19. W14-W15

20. L1-W16

21. L2-W17

22. L3-W18

23. L4-W19

24. W20-W21

25. W22-W23

26. L5-W24

27. L6-W25

28. W26-W27

29. L7-W28

W29 is the "second winner" and here you can either have or not have the game

 

30. W7-W29

to get the real winner.

 

Note that the main KO matches should probably be twice as long than the consolation KO matches since for each main KO round there are two consolation KO rounds.

 

Also note that if someone wins every game but loses game 30, they'll have lost the tournament despite losing only one game. This is a little unfair but not really, they could have lost as well but then they'd have to win another few games to get to the real final. Look at L7 they had to play match 29 to qualify, of L1 who had to play matches 20, 24, 26, 28 and 29 to qualify as opposed to W1 who had to play only games 5 and 7.

[gwnn]

The only easy way I see of applying this format to twenty-three teams is to have a phantom team that always loses. That would mean that you are favouring two teams directly since they now have a 50% chance of getting on the main KO as opposed to 33% of others and then in the consolation there will be a second placed team who is lucky and gets a bye. I guess you could have a 3-way match in the consolation KO so suppose H3 is a phantom team then games 10, 11 and 16 could be a 3-way with 1 winner. In this case we are favouring a few teams but I see no good way out of this.

 

Any ideas?

[bluejak]

You cannot avoid "favouring" some teams to get a 23 team double k-o movement. The Schapiro Spring Foursomes was originally designed for 64 teams, and an excellent alternative works for 48 teams. But since they never get either of these numbers, every year some teams have an advantage from the draw. Just do not worry about it, work something out that works, seed if necessary, and then do a fair draw so that the teams with the "advantage" are randomised.

 

I do not understand most of the replies anyway: we do not want a "consolation" knock-out: the request is for a format for double knockout.

 

Let us try this:

7 triples

1 straight match

Now you have 8 undefeated, 15 once defeated

 

Undefeated:

4 strained matches

Once defeated:

5 triples

Now you have 4 undefeated, 9 once defeated

 

Undefeated:

2 straight matches

Once defeated:

3 triples

Now you have 2 undefeated, 5 once defeated

 

Undefeated:

1 straight match

Once defeated:

1 triple

1 straight match

Now you have 1 undefeated, 3 once defeated

 

Semi-final

2 straight matches

The undefeated team gets it choice of opponents, and extra boards if it is losing after the normal number

 

Final

1 straight match

If the undefeated team did not play extra boards in the semi-final, then extra boards if it is losing after the normal number

 

A consolation event for teams once they have lost twice seems sensible.

[gwnn]

Well 'consolation' is indeed not really a good word on my part because you can still win the event from there, it was just how we always called them. I don't really like bluejak's format because I prefer to have byes and favoured teams as early as possible, not so late as he appears to have it (in the third round of the once defeated tournament), and have the rest of the tournament symmetric.

[campboy]

Bluejak's suggestion looks excellent to me. Triples are very much better than having byes. Having triples in the once-defeated pool and straight matches in the undefeated is nice too.

 

At the quarter-final stage, where you have to break symmetry in the once-defeated pool, why not do so by playing the two teams who lost in the previous round together in the straight match? By doing so you give the advantage (of only needing to beat one other team) to the teams who have in some sense earned it, and avoid gwnn's worry of having randomly favoured teams late on.

[gwnn]

Yes campboy that is 100% symmetric, I like it!

 

But you should still get a 24th team!! KO's are cooler than 3-ways.

[MBV53]

thanks to all for their nice formats. Still throw some more light on starting with knock out matches[ seeding & ranking the teams to be considered]. stage Two main winning group should be 16 teams. example- among 23 teams top seed gets bye in 1st KO ,rest play KO and 11 teams qualify making 12. now adding 4 teams from loosers [like BBO total point score events- Best loosers] making 16 in winning group and rest in loosing group. To go out of tourney a team needs to be knocked out twice. and semifinal should be W1 vs L2, W2 vsL1. pl think and advice.

MBV53

[bluejak]

You have not given us any idea of the time involved. This might work if matches are played by arrangement, but if you are playing a weekend event - for example - I should not want to play in an event where you sit out a whole match, and as a player would consider this vastly inferior to a method such as the one I described.

[Vampyr]

Well 'consolation' is indeed not really a good word on my part because you can still win the event from there, it was just how we always called them.

It is called a repechage.

[suprgrover]

The only problem with 3-way matches is that solving the bridge equivalent of the 3-body problem is not always easily solvable.

 

In New York City, the local district has an annual double knockout event, with one match played per month, generally in participants' homes. A few years back, its event had 22 teams--the bracket chart is here. (From what I can tell, to add a 23rd team, have 23 play 10 in the first round; have 23 receive a bye in the second round of the once-defeated bracket; and have 15 play 23 in the third round.) The conditions of contest for that year are here as well.

[axman]

The only problem with 3-way matches is that solving the bridge equivalent of the 3-body problem is not always easily solvable.

 

In New York City, the local district has an annual double knockout event, with one match played per month, generally in participants' homes. A few years back, its event had 22 teams--the bracket chart is here. (From what I can tell, to add a 23rd team, have 23 play 10 in the first round; have 23 receive a bye in the second round of the once-defeated bracket; and have 15 play 23 in the third round.) The conditions of contest for that year are here as well.

I strongly dislike byes.

 

I think it is better to conduct 3-ways of two concurrent sessions [same day to minimize expenses]

 

3-ways have either 0 [as is the case when each team is 1-1] or 1

survivors OR use a tie break to guarantee a survivor in the defeated bracket

 

Minimize the number of times a team is in a 3-way

[MBV53]

The event Duration 4 full days.

[mrdct]

Have a look at the format of the Yeh Bros Cup which works quite well for a field of 24 teams, so 23 shouldn't be much of a problem.

 

Basically the field plays 10 rounds of swiss over the first two days to qualify the top 16 teams to the KO stage.

 

In the KO stage, the top 8 team form the top bracket and the next 8 teams form the lower bracket. The top bracket plays double KO (losers move to the lower bracket) and the lower bracket plays single KO. Accordingly, at the 3rd round of the KO, the upper bracket has two undefeated teams and the lower bracket has six surviving teams who then play two triangles, the winners of which join the loser from the round 3 upper bracket match for a further triangle to decide the finalist to play-off against the single undefeated team from the upper bracket.

 

The diagram here explains it all.

[Vampyr]

Basically the field plays 10 rounds of swiss over the first two days to qualify the top 16 teams to the KO stage.

This competition consists of privately played matches. I think that the logistics of running a Swiss competition would be difficult to manage...

 

I have never been in a three-way match in this sort of competition, though I suppose it could be managed. A lot of matches might have to be played at the local club!

 

If I had to choose, I would prefer a straight knockout with some byes than some head-to-head matches and some three-ways. The English Spring Fours (a double elimination tournament) are played in the latter manner, with two undefeated teams emerging from the "triangles", so it is brutally unfair to the teams that get drawn in a head-to-head match the first round.

[bluejak]

One undefeated team emerging from the triangles, and it is hardly 'brutally unfair'. I really do not think that people pay hundreds of pounds and go all the way to Stratford to sit in the bar.

 

Really, I think it simple enough: if the matches are played by agreement over a period, byes are fine, though of course they are even more 'brutally unfair' than the Spring Fours model, since teams with a bye get a much better chance of going forward. If they are played at a venue over a weekend, lots of byes is not the answer.

 

:D

 

Going back to this 'brutally unfair' bit, suppose you decide to reduce 23 teams to 8 undefeated. First there was my suggestion:

 

Round 1: 7 triples, one straight match.

 

21 teams have a 33% chance of being undefeated, 2 teams have a 50% chance of being undefeated.

 

Second, using byes:

 

Round 1: 1 bye, 11 straight matches

 

Now you have 12 undefeated, so you have a second round

 

Round 2: 4 byes, 4 straight matches

 

Ok, that is 8 undefeated. I presume the bye in the first round must play in the second.

 

So, let us see the odds:

 

The team that sat out the first round: 50% chance of being undefeated.

The four matches in the first round which lead to byes in the second round: 8 teams with a 50% chance of being undefeated.

The remaining seven matches in the first round: 14 teams with a 25% chance of being undefeated.

 

Now, how on earth can 9 teams with a 50% chance of being undefeated, and 14 teams with a 25% chance of being undefeated possible be fairer than 21 teams have a 33% chance of being undefeated, 2 teams have a 50% chance of being undefeated?

 

Of course, I have not looked at the question of the once defeated teams, but I expect it easy to prove that byes mean it is considerably less fair than triples for the same reason: byes give too much of an advantage to teams that get them.

[gwnn]

bluejak if you have byes, you always have them in the first round. You would have 9 byes, i.e. 7 straight matches in the first round. You can't have byes after some teams have been eliminated, it feels very unfair. I do not intend to post this as a rebuttal to your post, but just a minor correction - in fact I think the conclusion is the same (9 teams with 50% chances of qualifying and 14 teams with 25%).

[bluejak]

Ok, fair comment, but as you say it comes to much the same thing. I also would not like to be the TD who explained to all those teams why they are not getting a game on the Friday evening.

[Vampyr]

One undefeated team emerging from the triangles, and it is hardly 'brutally unfair'. 

None of these teams will be twice-defeated in the third round, whereas a quarter of the people in head-to-head matches will be. I do think that this is very unfair. Perhaps playing all of the first-round matches as triangles, with rules to get the right number of undefeated teams in round three, is the best solution.

[bluejak]

I suggested:

 

Let us try this:

7 triples

1 straight match

Now you have 8 undefeated, 15 once defeated

 

Undefeated:

4 straight matches

Once defeated:

5 triples

Now you have 4 undefeated, 9 once defeated

Of the 21 teams who played in the triples, 10 teams are twice defeated. Of the 2 teams who played in the straight match, one will be twice defeated half the time.

 

That does not seem 'brutally unfair', and 'None of these teams will be twice-defeated in the third round, whereas a quarter of the people in head-to-head matches will be.' just is not true.

[campboy]

I think you are talking at cross-purposes. Vampyr is talking about the Spring Fours. In that, being in a triple for the first two rounds guarantees that you will be in the third round, whereas the people who play straight matches for the first two rounds may get knocked out completely.

[bluejak]

Oh? I thought we were trying to decide what is best for a 23 team double elimination k/o.

[Vampyr]

Oh?  I thought we were trying to decide what is best for a 23 team double elimination k/o.

Yes, and I have told my reasons why I believe that a combination of head-to-head and triangular matches is very poor. For instance, in a 23-team knockout. The Spring Fours was used by way of example.

 

Sorry for the confusion. I hope this has cleared things up for you.

[campboy]

It seems that the reason that the Spring Fours format has the problem you describe, though, is that in the Spring Fours a triangular match lasts for two rounds. One-round triangular matches do seem to be much fairer than byes -- having a bye in round one certainly means you can't be twice-defeated after round two!