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Arimaa >> Events >> WC ; wrong pairing ??
(Message started by: chessandgo on Jan 6th, 2008, 11:32am)

Title: WC ; wrong pairing ??
Post by chessandgo on Jan 6th, 2008, 11:32am
Hi all,

I notice the pairings are not the expected swiss pairings, but folding pairings. Did I misunderstood the rules ? Or did they change ? Or is there a problem ? I'll be sending an email to Omar and Ron just in case.

Bye

Jean

Title: Re: WC ; wrong pairing ??
Post by Fritzlein on Jan 6th, 2008, 3:09pm
You have it right, Jean, these are not Swiss pairings.  Omar told me he would correct the situation, hopefully by Sunday night (our time zone).  But whether or not he can get his software fixed in time, the first round will be played with Swiss pairings rather than the ones sent out yesterday.

Title: Re: WC ; wrong pairing ??
Post by Fritzlein on Jan 6th, 2008, 9:45pm
The correct round one pairings are now up.  Thanks, Omar!

Title: Re: WC ; wrong pairing ??
Post by Fritzlein on Jan 13th, 2008, 3:20pm
Hmm, it looks like the round 2 pairings are wrong too.  Woh should play megamau, not Aamir, and that messes up lower pairings too.  Omar, did you use the old pairing program instead of the corrected one?

Title: Re: WC ; wrong pairing ??
Post by Adanac on Jan 20th, 2008, 3:40pm
I have a question about the round 3 pairings.  I agree that Omar is the highest rated 1-1 player, and thus plays against woh.  And subs2000 is the lowest rated 1-1 player and plays against megamau.

That leaves 10 players with identical 1-1 records and identical strength of schedule.  So shouldn't the matchups be?:

jdb vs fritzleinforpresident
naveed vs froody
mistre vs ChrisB
ArifSyed vs Aamir
Camelback vs Emaad

Am I missing something?

Title: Re: WC ; wrong pairing ??
Post by Fritzlein on Jan 20th, 2008, 3:44pm
I'm pretty sure the round three pairings are wrong too, according to the algorithm outlined in the rules.  The pairings as they are posted now are:

Fritzlein vs. arimaa_master
chessandgo vs. 99of9
Adanac vs. PMertens
woh vs. omar

mistre vs. jdb
ArifSyed vs. naveed
camelback vs. fritzlforpresident
Emaad vs. ChrisB
froody vs. Aamir

subs2000 vs. megamau
Fisma vs. soldier
zackry vs. Amina
Sana vs. silump5

I agree with the top four pairings and the bottom four pairings.  One of the twelve players who is 1-1 must play up to make the top group even, and one must play down to make the bottom group even.  Omar is the only 1-1 player with three tiebreak points, and subs2000 is the only 1-1 player with one tiebreak point, so Omar must play up and subs2000 must play down.  So far so good.

However, when it comes to the remaining ten players who are all 1-1, they all have two tiebreak points as well.  For each of them, if you add up the wins of their two opponents, you get two wins.  Since there is no in-tournament criterion for saying which of these players has performed better, you have to fall back on pre-tournament rating.  In this case the order is:

jdb
naveed
mistre
ArifSyed
camelback
fritzlforpresident
froody
ChrisB
Aamir
Emaad

Swiss pairing in this group mandates

jdb vs. fritzlforpresident
naveed vs. froody
mistre vs. ChrisB
ArifSyed vs. Aamir
camelback vs. Emaad

Please double-check your pairing software to see if it is ordering the middle group correctly.  It might be that it is treating the second game differently than the first game, which it should not, according to the algorithm.  

If you think your program is correct, I'd like to see the debugging output so I can find where I made my error.  Thanks in advance!

Title: Re: WC ; wrong pairing ??
Post by Fritzlein on Jan 20th, 2008, 3:45pm

on 01/20/08 at 15:40:10, Adanac wrote:
Am I missing something?

Heheh, there's a former player-of-Swiss-chess-tournaments talking!  Looks like you beat me to it, Adanac.

Title: Re: WC ; wrong pairing ??
Post by arimaa_master on Jan 21st, 2008, 4:07am

on 01/20/08 at 15:44:03, Fritzlein wrote:
Fritzlein vs. arimaa_master
chessandgo vs. 99of9
Adanac vs. PMertens
woh vs. omar

I agree with the top four pairings ...


I simply do not agree with this pairingl :D (specially with the first one :))

Title: Re: WC ; wrong pairing ??
Post by Fritzlein on Jan 21st, 2008, 8:01am
Hehe, you would rather play chessandgo?  ;-)  But don't worry, I will lose to you in round three because I want to avoid playing chessandgo in round four, which will happen if all the favorites win...

Title: Re: WC ; wrong pairing ??
Post by omar on Jan 21st, 2008, 8:26am
Thanks for noticing this Greg and Karl. Fortunately it was just an operator error and not a problem with the pairing algorithm.

The result of round 1 had been counted twice. I've fixed it and here is the current tournament state file:

http://arimaa.com/arimaa/wc/2008/rounds/tournState

Title: Re: WC ; wrong pairing ??
Post by Fritzlein on Jan 21st, 2008, 10:01am
Thanks for fixing it, and thanks for the link to the tournament state so I can double-check my commentary page.

Title: Re: WC ; wrong pairing ??
Post by mistre on Jan 21st, 2008, 2:35pm
I am glad someone noticed this and it is fixed.  It would have been very harsh for either JDB or myself if we had to face each other in Round 3.

Title: Re: WC ; wrong pairing ??
Post by arimaa_master on Jan 22nd, 2008, 5:25am

on 01/21/08 at 08:01:59, Fritzlein wrote:
Hehe, you would rather play chessandgo?  ;-)  But don't worry, I will lose to you in round three because I want to avoid playing chessandgo in round four, which will happen if all the favorites win...


:D  ok, I will remind you that after our game :)   (I prefer my opponent to be  in this order: woh, omar,, adanac, 99of9, PMertens, Fritzlein, Chessandgo). The reason is obvious ;).

Title: Re: WC ; wrong pairing ??
Post by Fritzlein on Jan 22nd, 2008, 10:52am
Hmm, you have raised PMertens two spots from his 2008 tournament seeding but lowered him a spot from his finish in the 2007 World Championship.  It's always interesting to see people's subjective rankings.

In any event, the best opponents in Swiss tournaments are not always so clear.  I could reason that if I win our game, in round four I will probably lose to either chessandgo or PMertens, and as long as I am going to lose I would rather lose to chessandgo (who will get me the full six tiebreaker points) than to PMertens (who will gloat about his victory, then blunder horribly in the next round, costing me tiebreaker points).  :P



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