Author: Uri Blass
Date: 13:53:33 01/20/01
Go up one level in this thread
On January 20, 2001 at 15:47:36, Robert Hyatt wrote: >On January 20, 2001 at 15:38:01, Uri Blass wrote: > >>On January 20, 2001 at 13:30:15, Ulrich Tuerke wrote: >> >>>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 ? >> >>Yes >>> >>>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. >> >>I think that the window should not be of constant width. >> >>There is no problem with a small window in the first fail low but I think that >>after failing low and not finding a better move it is better to increase the >>width of the window. >> >>I think that a rule to double the size of the window after failing low without >>finding a better move may be better. >> >>You can also use the previous changes in the evaluation to decide about the size >>of the window(if there were big changes then it suggest that the position is >>tactical and it is better to use a bigger window. >> >>In the relevant position >>Comet has a lot of fail low at depth 11 and not only 1,2 or 3 >> >>Here is the relevant position: >> >>[D]2r3k1/1q3pp1/2bP2rp/1p6/4pB2/pPR4P/P2Q1PP1/2R3K1 b - - 0 1 >> >>Comet needed a lot of iterations to get from +1 for black(at the end of >>iteration 10) to a better move at depth 11. >> >>The scores at depth 11 from white point of view >>-0.86,-0.59,-0.32,-0.05,+0.22,+0.49,+0.76,+1.03 before finding a better move. >> >>I am not sure about the +1.03 but I remember that after the +0.76 it failed low >>the last time and changed its mind to e3. >> >>It is better if it can get the following scores >> >>-0.86,-0.59,-0.05,+1.03 so it can changes its mind in 4 iterations instead of 8 >>iterations. >> >>Uri > > >Here I actually don't think it matters. Black seems to be losing, period. >Here is what Crafty sees on my PII/400 notebook: > > 8-> 3.68 0.56 1. ... Rxg2+ 2. Kf1 e3 3. Qxe3 Re8 > 4. Qd4 Bf3 5. d7 Rd8 6. Rc7 > 9 5.69 -- 1. ... Rxg2+ > 9 13.24 3.19 1. ... Rxg2+ 2. Kf1 e3 3. Bxe3 Rg6 > 4. Rxc6 Rxc6 5. Rxc6 Qxc6 6. d7 Rd6 > 7. d8=Q+ Rxd8 8. Qxd8+ > 9 14.53 ++ 1. ... e3!! > (2) 9-> 26.99 2.80 1. ... e36 > 10 29.07 ++ 1. ... e3!! > 10 48.52 1.99 1. ... e3 2. fxe3 Rxg2+ 3. Qxg2 Bxg2 > 4. Rxc8+ Kh7 5. R8c7 Qd5 6. Kh2 Qd2 > 7. R1c2 > 10-> 58.84 1.99 1. ... e3 2. fxe3 Rxg2+ 3. Qxg2 Bxg2 > 4. Rxc8+ Kh7 5. R8c7 Qd5 6. Kh2 Qd2 > 7. R1c2 > 11 1:05 1.93 1. ... e3 2. fxe3 Rxg2+ 3. Qxg2 Bxg2 > 4. Rxc8+ Kh7 5. Kh2 Qf3 6. d7 Qxh3+ > 7. Kg1 Qxd7 8. Kxg2 Qd2+ 9. Kf3 Qxa2 > (2) 11-> 1:28 1.93 1. ... e3 2. fxe3 Rxg2+ 3. Qxg2 Bxg2 > 4. Rxc8+ Kh7 5. Kh2 Qf3 6. d7 Qxh3+ > 7. Kg1 Qxd7 8. Kxg2 Qd2+ 9. Kf3 Qxa2 > 12 2:05 1.77 1. ... e3 2. fxe3 Rxg2+ 3. Qxg2 Bxg2 > 4. Rxc8+ Kh7 5. R8c7 Qf3 6. h4 Bh3 > 7. R1c2 Bf5 8. R2c6 > >(note + scores are good for white) I think that e3 is enough for a draw. I analyzed the position and after 1...e3 2.fxe3 Rxg2+ 3.Qxg2 Bxg2 4.Rxc8+ Kh7 programs become less and less optimistic. When I see positive score for white that goes down and continues to do it then I suspect that something in the evaluation is not correct. Uri
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