Swiss Pairing issues

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David Sedgwick
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Swiss Pairing issues

Post by David Sedgwick » Mon Aug 09, 2010 12:55 pm

Phil Makepeace wrote:Hodgson started with ½/2 in 2000, after bizarrely - but apparently correctly - being paired against Speelman.
It was certainly correct and it wouldn't be regarded as bizarre by an arbiter. This sort of thing is common when you have very few drawn games in the first round, although of course most instances are far less high profile.

Suppose you have 50 players, so that the first round pairings are 1 v 26, 27 v 2, etc. (assuming 1 has White). Now suppose that 27 v 2 and 3 v 28 are drawn, but no other games. The only Round 2 pairings which avoid a float or a colour transfer are 2 v 3 and 28 v 27.

This doesn't happen if you accelerate the pairings, which may be a slight argument in favour of so doing.

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Re: British Championship: First round losers who won the tit

Post by Alex Holowczak » Mon Aug 09, 2010 1:10 pm

David Sedgwick wrote: It was certainly correct and it wouldn't be regarded as bizarre by an arbiter.
It may well be correct, but I can think of few arbiters who would be happy to pair 2 v 3 and 28 v 27 if they were the only 4 players in a scoregroup! You have to brace yourself for the arguments...

Kevin Thurlow
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Re: British Championship: First round losers who won the tit

Post by Kevin Thurlow » Mon Aug 09, 2010 1:36 pm

"It may well be correct, but I can think of few arbiters who would be happy to pair 2 v 3 and 28 v 27 if they were the only 4 players in a scoregroup! You have to brace yourself for the arguments..."

I might not be happy, but I'd do it! If you fiddle the draw to avoid 2 v 3, would you fiddle it to avoid 6 v 3, or 8 v 3, or 10 v 3? Where do you decide it's ok?
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Alex Holowczak
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Re: British Championship: First round losers who won the tit

Post by Alex Holowczak » Mon Aug 09, 2010 2:10 pm

Kevin Thurlow wrote:"It may well be correct, but I can think of few arbiters who would be happy to pair 2 v 3 and 28 v 27 if they were the only 4 players in a scoregroup! You have to brace yourself for the arguments..."

I might not be happy, but I'd do it! If you fiddle the draw to avoid 2 v 3, would you fiddle it to avoid 6 v 3, or 8 v 3, or 10 v 3? Where do you decide it's ok?
Sure, you would never fiddle the draw! I can just picture a nation of arbiters reading 2 v 3 and 28 v 27 on their pairing boards, realising it's correct, and sighing to themselves...

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John Saunders
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Re: British Championship: First round losers who won the tit

Post by John Saunders » Mon Aug 09, 2010 4:56 pm

This thread started promisingly but has already nosedived into one of the two most mind-numbingly dull discussion subjects in the whole of chess - Swiss pairings (the other one being grading). Enough already! We have a forum board for grading - we should have another one for Swiss pairing discussions. Any mention of them outside those areas should be punished with the full rigour of any law that Carl and co devise. Use your imagination and be as cruel and inhumane as you wish, administrators.
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Re: British Championship: First round losers who won the tit

Post by Roger de Coverly » Mon Aug 09, 2010 5:48 pm

David Sedgwick wrote:The only Round 2 pairings which avoid a float or a colour transfer are 2 v 3 and 28 v 27
What are the circumstances in which a colour transfer takes place? With a win with Black in the first round at Sunningdale in May and being top of the second half of the "1 point" score group, I was expecting either the number 1 seed Guliyev or the number 2 seed Simon Williams but presumed that I would get Simon as he was due Black. In the event I got Guliyev with Black. Any "preparation" for playing Simon with White wasn't entirely wasted as I was paired with him in round 4.

Being an e2e4 event, I'd imagine the pairings used the rules of Swiss Master.

http://www.e2e4.org.uk/sunningdale/May2010/open.htm

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Re: British Championship: First round losers who won the tit

Post by Alex Holowczak » Mon Aug 09, 2010 6:01 pm

Roger de Coverly wrote:
David Sedgwick wrote:The only Round 2 pairings which avoid a float or a colour transfer are 2 v 3 and 28 v 27
What are the circumstances in which a colour transfer takes place? With a win with Black in the first round at Sunningdale in May and being top of the second half of the "1 point" score group, I was expecting either the number 1 seed Guliyev or the number 2 seed Simon Williams but presumed that I would get Simon as he was due Black. In the event I got Guliyev with Black. Any "preparation" for playing Simon with White wasn't entirely wasted as I was paired with him in round 4.

Being an e2e4 event, I'd imagine the pairings used the rules of Swiss Master.

http://www.e2e4.org.uk/sunningdale/May2010/open.htm
Well, from what I've read there (with possible errors due to rushing) the 1 scoregroup had:
10 whiteseekers: 1 3 5 6 8 10 11 12 13 14
4 blackseekers: 2 4 7 9

I can't be sure that those 14 players are in seeding order, so I can't do the draw in the rush I'm currently in. You need 7 whiteseekers and 7 blackseekers, so in this case, there would have to be three colour transfers.

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Re: British Championship: First round losers who won the tit

Post by David Sedgwick » Mon Aug 09, 2010 6:07 pm

John Saunders wrote:This thread started promisingly but has already nosedived into one of the two most mind-numbingly dull discussion subjects in the whole of chess - Swiss pairings (the other one being grading). Enough already! We have a forum board for grading - we should have another one for Swiss pairing discussions. Any mention of them outside those areas should be punished with the full rigour of any law that Carl and co devise. Use your imagination and be as cruel and inhumane as you wish, administrators.
I received your final issue of BCM today. At least I know now why you failed to commission me to write an article about the most interesting Swiss Pairing issues which arose during your tenure, Hodgson v Speelman being one such.

Carl, please can you split the thread, before it gets any bigger?

I'll leave it to Sean to comment as he sees fit on Roger's question about Sunningdale.

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IM Jack Rudd
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Re: British Championship: First round losers who won the tit

Post by IM Jack Rudd » Mon Aug 09, 2010 6:12 pm

Colour transfers are chosen according to the following:

(a) Find the players who are best suited to colour transferring, based on their preceding colour sequences. Carry on doing this until you've identified a group of potential transferees at least the size of the number of transfers needed. Then:
(i) If this gives you exactly the right number of colour transfers, transfer them and do the draw.
(ii) If this gives you more than enough potential colour transfers, transfer all the ones best suited to colour-transferring. Then, out of the final group of equally-possible colour transfers, transfer the ones who give you the set of pairings that fits in best with the seedings.

Sean Hewitt

Re: British Championship: First round losers who won the tit

Post by Sean Hewitt » Mon Aug 09, 2010 6:52 pm

Roger de Coverly wrote:
David Sedgwick wrote:The only Round 2 pairings which avoid a float or a colour transfer are 2 v 3 and 28 v 27
What are the circumstances in which a colour transfer takes place? With a win with Black in the first round at Sunningdale in May and being top of the second half of the "1 point" score group, I was expecting either the number 1 seed Guliyev or the number 2 seed Simon Williams but presumed that I would get Simon as he was due Black. In the event I got Guliyev with Black. Any "preparation" for playing Simon with White wasn't entirely wasted as I was paired with him in round 4.

Being an e2e4 event, I'd imagine the pairings used the rules of Swiss Master.

http://www.e2e4.org.uk/sunningdale/May2010/open.htm
Hi Roger,

Always happy to explain our pairings, as GM Cherniaev will tell you :lol: However, in doing so I may have to beg John's humble forgiveness!

Our pairings are made in accordance with FIDE swiss pairing rules which can be found here http://www.fide.com/fide/handbook.html? ... ew=article

In round 2, there were 14 players on 1/1. There were 10 white seekeers and 4 black seekers - so we know straight away that 3 white seekers will have to be unlucky and get a second black.

So we now pair top half v bottom half and get

A. GM Guliyev, Namig 2533 w De Coverly, Roger D 2116 w
B. GM Williams, Simon K 2527 b Brown, Thomas 2087 b
C. GM Arkell, Keith C 2456 w Coates, David H 2084 w
D. FM Slavin, Alexei 2374 b Merry, Alan 2074 w
E. FM Radovanovic, Jovica 2351 w Atako, Chino 2065 w
F. Ynojosa, Felix Jose 2167 w Savage, Nicholas W 2024 w
G. Mihajlov, Svetoslav 2117 b Winter, Kevin 1898 w

We know that 3 white seekers need to play each other. However, we have 4 games featuring white seeker v white seeker (A, C, E & F) and this is because B had black seeker v black seeker.

So we transpose the 2nd and 3rd players in the lower half of the draw to get all the white seekers v black seekers that we can. That gives us the following pairings

A. GM Guliyev, Namig 2533 w De Coverly, Roger D 2116 w
B. GM Williams, Simon K 2527 b Coates, David H 2084 w
C. GM Arkell, Keith C 2456 w Brown, Thomas 2087 b
D. FM Slavin, Alexei 2374 b Merry, Alan 2074 w
E. FM Radovanovic, Jovica 2351 w Atako, Chino 2065 w
F. Ynojosa, Felix Jose 2167 w Savage, Nicholas W 2024 w
G. Mihajlov, Svetoslav 2117 b Winter, Kevin 1898 w

So now we know who is playing who, we just have to determine colours. For white seeker v black seeker that's easy. For white seeker v white seeker the highest seed gets the colour that they are due (in this case, white). So the finalised pairing (white player first) are

A. GM Guliyev, Namig 2533 w De Coverly, Roger D 2116 w
B. Coates, David H 2084 w GM Williams, Simon K 2527 b
C. GM Arkell, Keith C 2456 w Brown, Thomas 2087 b
D. Merry, Alan 2074 w FM Slavin, Alexei 2374 b
E. FM Radovanovic, Jovica 2351 w Atako, Chino 2065 w
F. Ynojosa, Felix Jose 2167 w Savage, Nicholas W 2024 w
G. Winter, Kevin 1898 w Mihajlov, Svetoslav 2117 b

Which by a happy coincidence is the pairings we had in Round 2. :-)

Perhaps that's why we are congress of the year :D
Last edited by Sean Hewitt on Mon Aug 09, 2010 9:06 pm, edited 1 time in total.

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Wilf Arnold
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Re: Swiss Pairing issues

Post by Wilf Arnold » Mon Aug 09, 2010 8:56 pm

In round 2, there were 14 players on 1/1. There were 10 white seekeers and 4 black seekers - so we know straight away that 3 black seekers will have to be unlucky and get a second black.
Black seekers aren't unlucky to get a second black as that's what they're seeking!

On the other hand white seekers who get a second black......
Perhaps that's why we are congress of the year :D
:wink:

Sean Hewitt

Re: Swiss Pairing issues

Post by Sean Hewitt » Mon Aug 09, 2010 9:06 pm

Wilf Arnold wrote:
In round 2, there were 14 players on 1/1. There were 10 white seekeers and 4 black seekers - so we know straight away that 3 black seekers will have to be unlucky and get a second black.
Black seekers aren't unlucky to get a second black as that's what they're seeking!

On the other hand white seekers who get a second black......
Perhaps that's why we are congress of the year :D
:wink:
There's always one :lol:

Andy McCulloch
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Re: Swiss Pairing issues

Post by Andy McCulloch » Tue Aug 10, 2010 12:10 am

Odd change of title in this thread

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Christopher Kreuzer
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Re: Swiss Pairing issues

Post by Christopher Kreuzer » Tue Aug 10, 2010 12:19 am

Andy McCulloch wrote:Odd change of title in this thread
It started as another thread, and I wanted to post something in response to the first post, but can't find that now! :shock:

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IM Jack Rudd
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Re: Swiss Pairing issues

Post by IM Jack Rudd » Tue Aug 10, 2010 12:21 am

Christopher Kreuzer wrote:
Andy McCulloch wrote:Odd change of title in this thread
It started as another thread, and I wanted to post something in response to the first post, but can't find that now! :shock:
The original thread's still in the Chess History section.

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