Author: Uri Blass
Date: 14:52:20 02/02/06
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On February 02, 2006 at 17:44:30, Uri Blass wrote: >On February 02, 2006 at 16:07:20, George Tsavdaris wrote: > >> I noticed a strange behaviour and definitely a bad one from latest Rybka, and >>for Winfinder so that means it should be a general bad behaviour of Rybka >>family:-) Possible bug that prevents correct analysis..... >> >> This behaviour is noticed at Fritz 8 GUI(i haven't tried Arena yet). It is also >>happening at Deep Fritz 8 GUI. It must be a hashproblem or something..... >> Conditions(I'll describe the procedure i followed--Keep in mind that the values >>for the seconds i've made analysing between the moves should not play any role >>at all and different values would produce the problem again): >> >>Set the following game: >> >>[Event "??"] >>[Site ""] >>[Date "2005.01.03"] >>[Round "?"] >>[White "Tsavdaris"] >>[Black "????"] >>[Result "1-0"] >>[PlyCount "54"] >>[EventDate "2005.??.??"] >> >>1. e4 e5 2. f4 d5 3. exd5 exf4 4. Nf3 Nf6 5. c4 c6 6. Nc3 cxd5 7. d4 Bb4 8. Be2 >>Ne4 9. O-O Bxc3 10. bxc3 Nxc3 11. Qc2 Nxe2+ 12. Qxe2+ Be6 13. Ba3 dxc4 14. d5 >>Qxd5 15. Rad1 Qb5 16. Nd4 Qb6 17. Kh1 Nd7 18. Rxf4 O-O-O 19. Nxe6 Qxe6 20. >>Rxc4+ Kb8 21. Qxe6 fxe6 22. Rcd4 b5 23. Rxd7 Rxd7 24. Rxd7 Rc8 25. Bd6+ Ka8 26. >>Bc7 a6 27. Rxg7 Rf8 1-0 >> >>-Set Rybka as an engine, clear hashtables and set it to let's say 256 MB. >>-Go to move 14 for black and start analysis with Rybka(multivariation with 4 >>lines i had) for some seconds(4-5). >>-It displays the move Rad1 as best. Press the "Right Key" button from the >>keyboard in order the next move to be executed while the analysis will continue. >>-Press the "Right Key" button again after 1-2 seconds so the move Qb5 will be >>played. >>-Press the "Right Key" button again after 4-5 seconds so the move Nd4 will be >>played. >>-Press the "Right Key" button again after 1-2 seconds. >>Now Rybka displays 17.Rxf4 as the best move with -2.00 evaluation! >>So what? Well if we clear at that point the hashtables then Rybka displays the >>correct evaluation and correct move which is 17.Kh1 with a positive score. >> >> Also if we put the position with white at move 17 to play, to Rybka to analyse >>then we get the correct analysis. But if we have the analysis open from move 15 >>and continue up to move 17 for white we get 17.Rxf4???? >> >> >>Can anyone reproduce this.....? > >I could reproduce it in 3 option mode > >Here is the pv at depth 14 > >Tsavdaris, 2005 >rn2k2r/pp3ppp/1q2b3/8/2pN1p2/B7/P3Q1PP/3R1RK1 w kq - 0 1 > >Analysis by Rybka 1.01 Beta 13b 32-bit: > >1. -+ (-2.38): 17.Rxf4 >2. -+ (-2.38): 17.Kh1 >3. -+ (-2.53): 17.Bb2 > >(, 03.02.2006) > >depth 15: > >Tsavdaris, 2005 >rn2k2r/pp3ppp/1q2b3/8/2pN1p2/B7/P3Q1PP/3R1RK1 w kq - 0 1 > >Analysis by Rybka 1.01 Beta 13b 32-bit: > >1. -+ (-2.44): 17.Rxf4 >2. -+ (-2.44): 17.Kh1 >3. -+ (-2.59): 17.Bb2 > >(, 03.02.2006) > >one of the strenge things is that there is no pv for none of the lines > >Uri A simpler way to reproduce it is to start from the position after 15.Rad1 and make the game moves 15...Qa5 16.Nd4 Qb6 fast. I get the following analysis at depth 14: Tsavdaris, 2005 rn2k2r/pp3ppp/1q2b3/8/2pN1p2/B7/P3Q1PP/3R1RK1 w kq - 0 1 Analysis by Rybka 1.01 Beta 13b 32-bit: 1. -+ (-2.44): 17.Bb2 2. -+ (-2.45): 17.Rxf4 3. -+ (-2.45): 17.Kh1 (, 03.02.2006) Uri
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