[hrothgar]

Hi All

I'd like to throw out the following "offer".

From what I understand, the bible on bridge movements is a recent publication titled "Movements, A Fair Approach", co-authors Olof Hanner and Per Jannersten. English version by Barry Rigal.

Hanner is a professional mathematician and used to be the Chief Tournament director in Europe. His goal in producing the book was to create fair/balanced movements. From my perspective, the BEST course of action would be to contact Hanner directly and ask him to tackle the problem. I think that he probably has the best perspective on the issue.

If this proves impractical for some reason - for example, Hanner can't be tracked down or is unwilling to help - then I would be happy to buy a copy of the book and lend it to Fred or Uday or whomever would be doing the actual coding.

Let me know what folks think.

[Gerardo]

Dusan:
OK, didn't get your point.
Can you prove this (guess so, should be there by design)? Can you provide a few examples (didn't find much)? Few I saw, it had the same principle of N following N-1 (1 following the highest odd), so this properties depends on choosing the (a) right first round. Is this right?
If so, is there a way to find it? Maybe we should have first round hardcoded?

It is a strong condition, it limits the number of players (in a section), as it simply does not scale.
Also, it is impossible to meet in swiss pairs in proper time, and probably not at all.

Richard:
I'm interested, of course.
However, we should be able to specify what we look in a movement, even if that movement comes from <whoever>.

what conditions should a movement meet?

[Posleda]

Gerardo, on Feb 20 2004, 08:01 PM, said:

Can you prove this (guess so, should be there by design)? Can you provide a few examples (didn't find much)? Few I saw, it had the same principle of N following N-1 (1 following the highest odd), so this properties depends on choosing the (a) right first round. Is this right?
If so, is there a way to find it? Maybe we should have first round hardcoded?

It is a strong condition, it limits the number of players (in a section), as it simply does not scale.
Also, it is impossible to meet in swiss pairs in proper time, and probably not at all.

The sample movement and all others I have sent to uday was taken from book, written by Andrzej Wachowski, well-known Polish organizer. He says the movements were chosen by computer (brute force I think). I believe him. I can send all movements to you too. There is no need to find other movements.

Yes, you are right: N following N-1 is a principle, initial position may change tournament's behaviour (balance).

The number of players is not limited. Besides Full Howell there are so called Short Howell od Three Quarter Howell movements. You can use them, when number of rounds is greater than half of players (if equals, you use Mitchell instead). In our example with 14 players you can play from 8 to 13 rounds. Initial position is always different, the less rounds, the more sitting pairs (near to Mitchell).

Swiss pairs is another cup of tea.

Dusan

[Posleda]

hrothgar, on Feb 20 2004, 04:45 AM, said:

If this proves impractical for some reason - for example, Hanner can't be tracked down or is unwilling to help - then I would be happy to buy a copy of the book and lend it to Fred or Uday or whomever would be doing the actual coding.

Let me know what folks think.

Nobody can learn how to organize tournaments only from book without practice, I think. I am no Hanner or Jannersten, but small director from small country with hundreds offline tournaments on account. Some months ago I offered my help on the tournaments field, I am sorry to say without answer.

Dusan

[hrothgar]

Posleda, on Feb 20 2004, 05:03 PM, said:

Nobody can learn how to organize tournaments only from book without practice, I think. I am no Hanner or Jannersten, but small director from small country with hundreds offline tournaments on account. Some months ago I offered my help on the tournaments field, I am sorry to say without answer.

Dusan

Funny that. I see this as an example of an essentially "pure" statistics or signal processing problem. I'm unclear why significant amounts of practice with real world tournaments would be required.

Once the organizers have agreed to a basic set of design criteria, it simply remains to create an optimal algorithm.

Here is my take at a set of design criteria.

From my perspective, the primary design goal should be producing a "fair" movement subject to the constraint that the movement is broadly compatible with the number of boards that the organizers want to support. I am defining a fair movement as one in which each pair plays the same number of boards against every other pair in the tournament. I explictly note that I think that other criteria should be held subordinate to this goal.

The secondary design goal should be to guaruntee that pairs play a "reasonable" number of boards against one another. For all intents and purposes, a bridge tournament can be modelled as a sampling problem, with each board treated as an independent event. Basic stats suggests that the larger the number of samples, the closer that the sample mean will coverge on the population mean. I'm not sure what the "optimal" number of boards per round is, however, I lean towards three or four.

With this said and done...

As stage one, I would try to identify the set of "pure" movements that fulfill the selected designed criteria. Ignoring the trivial case in which the number of tables = 1, the simpliest case is when you have 4 pairs competing at two tables.

Here, we require 3 rounds to fully mesh the movement. We can create a balanced movement anytime that we are willing to run a tournament in which the total number of boards is an even multiple of 3.

In a similar fashion, if we have 6 pairs completing at 3 tables, we require 5 rounds to fully mesh the movement. We can create a balanced movement anytime that we run a tournament where the number of boards is an even multiple of 5.

When the number of pairs is relatively small, its fairly easy to create a balanced movement that will roughly accord with the organizers time/board constraints. However, these fully meshed movements start encountering problems when the number of players gets large. For example, suppose that we have 24 pairs, as is normal at an Abalucy event. In this case, supporting a fully meshed movement would require running a tournament where the number of boards was an even multiple of 23. While this movement successfully achieves our first criteria, it going to run into significant problems with criteria 2. No-one is going to bother sticking arround for a 69 board event to ensure that everyone plays an optimal number of boards against all possible opponents.

Thus we move to "Stage 2" of the our problem. Ideally, we should be able to partition any given tournament into a series of distinct sections, each of which will support an optimal number of rounds. For example, our set of 24 pairs can be partioned in three sets of eight pairs each. Each set can play 7 rounds of four boards each, requiring a total of 28 boards. Unfortunately, this type of movement doesn't allow us to compare results across sections - logically, you're running three separate tournaments each using the same set of boards. However, I strongly prefer this type of structure to one that "pretends" a false degree of accuracy.