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Subject: Re: odyssee2001-tournament: shredder4 cb - comet b27 ... interesting

Author: Ulrich Tuerke

Date: 10:30:15 01/20/01

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On January 20, 2001 at 09:56:57, Uri Blass wrote:

>On January 20, 2001 at 06:24:19, Thorsten Czub wrote:
>
>>
>>[Event "Odyssee2001-Tournament"]
>>[Site "k6-400, 40/120"]
>>[Date "2001.01.20"]
>>[Round "1"]
>>[White "Shredder4 Chessbits-style"]
>>[Black "Comet B27"]
>>[ECO "C99"]
>>[Result "*"]
>>
>>1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1
>>b5 7. Bb3 d6 8. c3 O-O 9. h3 Na5 10. Bc2 c5 11. d4 Qc7
>>12. Nbd2 cxd4 13. cxd4 Nc6 14. Nb3 a5 15. Be3 a4 16. Nbd2
>>Bd7 17. Nf1 Rfe8 18. Rc1 Qb7 19. Ng3 a3 20. b3 Rac8 21. Qd2
>>exd4 22. Nxd4 d5 23. Nxc6 Bxc6 24. e5 Ne4 25. Bxe4 dxe4
>>26. Nf5 Bf8 27. Nd6 Bxd6 28. exd6 Re6 29. Bf4 Rg6 30. Re3
>>h6 31. Rec3 *
>>
>>after Rec3 shredder4 got a fail-low and comet first considered
>>about Rxg2 with positive score for black, but now has changed
>>mind and says 0.47 for white when playing Rxg2+. now comet
>>says +0.74 for white.
>>
>>anyway - interesting game too.
>
>I see that CometB27 had a lot of fail low by 0.27 at iteration 11.
>
>I think that the decision about this constant number is not a good decision and
>it is better to increase the number after failing low.
>
>Comet needs a long time to find e3 at depth 11 because of this decision and had
>not enough time at tournament time control when other programs have no problem
>to find e3 at tournament time control.
>
>Maybe Uli can change the 0.27 design decision for the next rounds and to use
>bigger numbers after failing low without solving the fail low problem.
>
>Uri

If I got this right Uri, you are referring to the aspiration window treatment of
Comet. It uses a very small window, basically of constant width, which will be
just shifted in case of a verification search.
This way, one sometimes needs a lot of verification searches in fail low/high
cases.
I think that this is what you are referring to ?

However, the advantage is that this method speeds up the search im more quiet
positions.
I think that I will still stick to this - at least for a while.

Thx for your comments.

Uli



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