Author: George Tsavdaris
Date: 13:07:20 02/02/06
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.....?
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