How is a DE round built?

[BanksySan]

I am a programmer who used to fence a few years ago. I am writing a program which does what En Guard does.. only better. I have come into a problem though. DE allocation!!

What are the rules of DE allocation. If you have n fencers in the round how are they distributed?

I am going in circles. Any advise?

[KShan5[PrFC]]

Well obvioulsy it is not as good as En Guard yet.

[AndrewH]

Assuming that the DE's are run after pools? Well, calculate the indicators for each fencer and give each one a rank. Now decide whether you want to include everyone (round up to the nearest power of 2) or cut to a power of 2. Let's say you're going to include everyone, and there's 28 fencers.

1) Find the next highest power of 2 (in this case, 32)
2) For each fencer, find their opponent. Mathematically:
n = number of fencers to begin with (32)
Fencer 1's opponent is (n + 1) - 1
Fencer 2's opponent is (n + 1) - 2
...
Fencer f's opponent is (n + 1) - f

Now because you started with 28 fencers, you need to create 4 more "fencers" to put into the table, they act as byes and are ranked after the 28 regular fencers. If a fencer fences a bye, he gets an automatic win.

Does that clear it up for you?

[BanksySan]

Cheers Andrew.

I have got that far, the problem comes when creating the DE tree.

If you have 28 fencers then you will be running a short 32.

1v32 & 2v31 will have the outside tracks in the tree, thus ensuring that they do not meet each other until the final (assuming they don't loose to a fencer of a lesser seeding). Where do 3v30 or 10v22 go?

[michel]

Originally posted by BanksySan
Cheers Andrew.

I have got that far, the problem comes when creating the DE tree.

If you have 28 fencers then you will be running a short 32.

1v32 & 2v31 will have the outside tracks in the tree, thus ensuring that they do not meet each other until the final (assuming they don't loose to a fencer of a lesser seeding). Where do 3v30 or 10v22 go?

I think you mean in which position in the 1st round of DE goes 3v30 or 10v22. Right ?
If you want to automatically put it in the tree, I am not sure there is an easy way to find it mathematically.
Perhaps the best way is to constitue a pattern for each type of DE (8, 16, 32, 64, 128, 256...), and to use it on request.
I think Engarde uses this method, and this is the method i would use if I wanted to build such a software.

[BanksySan]

Thanks that's a good idea. It would certianally be easier (if not as satisfying). I think I am going to go for a slightly different approch now. I was looking to be able to build a round individually from the others from the other rounds given a seeding list.

I am going to do it you way.

Thanks again.

Dave

[michel]

About Engarde, the DE matches are designated by a letter and a number, the letter representing the round, and the number representing the place of the match in the round. And I think this is the way to build further round after the first one.
For example, the first match in the second round is between the winner of the matches # 1 and 2 of the first round, an so on.
The final match is designated by A1, semifinals by B1 and B2... So match D1 will be between winner of E1 and E2, match D7 between winners of E13 and E14, an so on.
In case of repechages, there are several brackets and matches in main bracket only have one letter and a number, and in repechage brackets 2 letters (letter of the brackets, and level in the braket, like about the main bracket) and a number.

[Army Fencer]

An example of the round of 64 used to be in the USFA rule book, but it isn't in the most current version. The governing body of the UK might have an example that you can look at.

[nahouw]

Originally posted by BanksySan
I am a programmer who used to fence a few years ago. I am writing a program which does what En Guard does.. only better. I have come into a problem though. DE allocation!!

What are the rules of DE allocation. If you have n fencers in the round how are they distributed?

I am going in circles. Any advise?

It is very easy to allocate fencers -- all fencers are allocated within the DE tableau of the final number + 1 -- i.e. if there are 32 people in the tableau, the number 16th fencer will fence the number 17th fencer -- a tableau of 32,. It follows a standard tennis table, if you are still perplexed.

[DHCJr]

I think their problem is how to set up the tree, not who fences whom.

The easiest way is to build the tree from the right. For example, if you have 2 people, it would we 1-2 for the finals. For 4, you have 1-4, 3-2 for the semi-finals. Then 8 would be 1-8, 5-4, 3-6, 7-2 for the quarter finals. If you notice, the new additions go where the dash went. That is why we have 3-6 and not 6-3.

Next 1-16, 8-9, 5-12, 13-4, 3-14, 11-6, 7-10, 15-2 and finally

1-32, 17-16, 8-25, 24-9, 5-28, 21-12, 13-20, 19-14, 11-22, 27-6, 7-26, 23-10, 15-18, 17-2.

If you keep up this formula, you can take it as high as you want.

[BanksySan]

I actually have that written on the bit of paper in frint of me. I have been staring at it for about 2 hours without seeing the wood for the trees. Thanks for clearing it up!!

Thanks for putting it in, it's helped!!

Thanks, to all of you for your help.

Dave