Author: blass uri
Date: 23:33:58 10/21/99
Go up one level in this thread
On October 21, 1999 at 23:01:15, Laurence Chen wrote: >On October 21, 1999 at 20:22:44, Thorsten Czub wrote: > >>Example why it is dangerous to use a program >>like Fritz6 in analysis for (e)mail-chess: >> >>In the moment i am playing a public game against >>anonymous person in a newsgroup. >> >>during the analysis i came to the following situation: >> >>after the moves >> >>[Event "mail-chess-game"] >>[Site "gambit-soft-board"] >>[Date "1999.10.22"] >>[Round "1"] >>[White "Thorsten Czub"] >>[Black "Anonymous called <Rudi>"] >>[Result "*"] >> >>1. d4 d5 2. e4 dxe4 3. Nc3 Nf6 4. f3 exf3 5. Qxf3 Qxd4 6. Be3 Qh4+ >>7. g3 Qg4 8. O-O-O Qxf3 9. Nxf3 c6 10. Bg2 Nbd7 11. Rhe1 e6 12. Nd4 Bc5 >>13. Na4 Bxd4 14. Bxd4 O-O 15. b3 Re8 16. Nb2 Nb6 17. Nd3 Nfd5 18. c4 Nf6 >>19. Bf3 Nfd7 20. Nf4 Kf8 21. Bb2 a5 22. Ba3+ Kg8 23. c5 a4 * >> >> >> >>the following position came on board of fritz6: >> >>Ich - Rudi >>r1b1r1k1/1p1n1ppp/1np1p3/2P5/p4N2/BP3BP1/P6P/2KRR3 w - - 0 1 >> >>fritz6 evaluated the position and the chances as follows: >> >> >>Analysis by Fritz 6: >> >>24.Txd7 >> -+ (-2.97) Tiefe: 1/3 00:00:00 >>24.Txd7 Sxd7 >> -+ (-3.31) Tiefe: 1/4 00:00:00 >>24.cxb6 >> = (0.16) Tiefe: 1/4 00:00:00 >>24.cxb6 Sxb6 >> = (0.16) Tiefe: 2/4 00:00:00 >>24.cxb6 >> = (0.00) Tiefe: 3/5 00:00:00 >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> µ (-1.22) Tiefe: 3/9 00:00:00 >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> µ (-1.22) Tiefe: 4/6 00:00:00 >>24.cxb6 axb3 25.Kb2 bxa2 26.h3 >> µ (-1.12) Tiefe: 5/13 00:00:00 1kN >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.h3 >> µ (-1.06) Tiefe: 6/16 00:00:00 7kN >>24.cxb6-- >> µ (-1.37) Tiefe: 7/11 00:00:00 8kN >>24.cxb6 >> µ (-1.37) Tiefe: 7/15 00:00:00 10kN >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.h3 e5 28.Td6 >> -+ (-1.56) Tiefe: 8/16 00:00:00 20kN >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 e5 28.Lc5 Sd7 >> -+ (-1.66) Tiefe: 9/17 00:00:00 43kN >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Te4 e5 28.Tde1 f6 >> -+ (-1.69) Tiefe: 10/20 00:00:00 158kN >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Te4 e5 28.Tde1 f6 >> -+ (-1.72) Tiefe: 11/26 00:00:01 506kN >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 e5 28.Lb2 f6 >> -+ (-1.78) Tiefe: 12/27 00:00:06 1909kN >>24.cxb6 axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 e5 28.Lb2 f6 >> -+ (-1.81) Tiefe: 13/31 00:00:30 10018kN >>24.b4 >> -+ (-1.78) Tiefe: 13/31 00:01:02 20891kN >>24.b4 Sc4 25.Lb2 Sxb2 26.Kxb2 e5 27.Sd3 f5 28.Lh5 Te7 >> -+ (-1.69) Tiefe: 13/33 00:01:29 30248kN >>24.b4 Sc4 25.Lb2 e5 26.La1 Sf6 27.Sd3 Le6 28.Sxe5 Sxe5 >> -+ (-1.59) Tiefe: 14/31 00:04:11 84912kN >> >>As you can see from the analysis above, fritz6 thinks >>it is 1.5 pawns up. >>A few main-lines before it came to the conclusion that >>cxb6 axb3 etc. is worth only 1.81 so it changes to >>b4 because it thinks this would be a better idea for >>white. >> >>Now we make 24.cxb6 and watch out what fritz6 says now : >> >>Ich - Rudi >>r1b1r1k1/1p1n1ppp/1Pp1p3/8/p4N2/BP3BP1/P6P/2KRR3 b - - 0 1 >> >>Analysis by Fritz 6: >> >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> = (0.09) Tiefe: 4/10 00:00:00 1kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> = (0.09) Tiefe: 4/10 00:00:00 1kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> = (0.09) Tiefe: 4/10 00:00:00 1kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> = (0.09) Tiefe: 4/10 00:00:00 1kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> = (0.09) Tiefe: 4/10 00:00:00 1kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> = (0.09) Tiefe: 4/10 00:00:00 1kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 >> = (0.09) Tiefe: 4/10 00:00:00 1kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 >> ² (0.28) Tiefe: 5/14 00:00:00 7kN >>24...axb3 >> = (-0.03) Tiefe: 6/14 00:00:00 20kN >>24...axb3-- >> ² (0.28) Tiefe: 7/16 00:00:00 49kN >>24...axb3 >> ² (0.28) Tiefe: 7/19 00:00:00 75kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 Sd7 28.Le4 e5 >> = (0.09) Tiefe: 8/22 00:00:01 322kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 e5 28.Ld6 g5 29.Sd3 >> = (0.00) Tiefe: 9/21 00:00:02 848kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 e5 28.Ld6 g5 29.Sd3 >> = (-0.03) Tiefe: 10/24 00:00:08 2685kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 e5 27.Kb3 f6 28.h3 Kf7 29.Sd3 >> = (-0.09) Tiefe: 11/28 00:00:33 9872kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 e5 >> = (-0.22) Tiefe: 12/29 00:02:01 37126kN >>24...axb3 25.Kb2 bxa2 26.Kxa2 Sxb6 27.Kb3 e5 28.Ld6 f6 29.Lh5 >> = (-0.19) Tiefe: 13/31 00:08:23 151133kN >> >> >> >>HOW can this be ? >> >>I guess it loads new piece-square-tables (preprocessing) >>with new values and gets a totally different >>impression from the position than ONE PLY before. >> >>it is obvious that this way the whole main-line >>computation of ONE PLY BEFORE was senseless time-wasting, >>since the new thought-computation gets a different >>point of view about the position. >> >>Guess you are a newbie in computerchess, guess >>you don't know about chess programs and guess you >>have bought this very strong program, the package >>says it got 2800 ELO performance against top-players. >> >>you trust this. >>and you analyse your games with it. >>you know that the longer you let fritz6 compute, >>the better the results will be. >> >>you have to consider about the position. >>and you get the one or the other evaluation from fritz6: >> >>one time it says black is 1.5 pawns ahead, >>and ONE ply later it says : oh - not a problem, only 1/5 >>of a pawn against white. >> >>So - many years we had genius having asymmetrically evaluations >>and main-lines. >>It had the same effect: you let it compute >>a long time about a position, it says 1.5 for black (e.g.) >>and you give it ONE PLY later and it says only 0.2 for >>black. >> >>This time Fritz6 replaces the Genius misbehaviour: >>i don't think it has an asymmetrical search, but i guess >>the preprocessing makes it reevaluate only the root- >>positions, without making sensible changes in the main-line. >>cxb6 was in the main-line of the 24th move. >>but this move was not moved on the board. >>One ply later the root position is another, fritz has to load >>new values in the tables, and suddenly the whole score changes >>1.3 pawns ? >> >>How can a chess-program come to sensible information with >>this type of behaviour ?? >>How can you trust the analysis of a chess program >>when it changes its mind this heavily ? >>How can you create a sensefull main-line when >>ONLY the root position gets somehow evaluated, and >>not the moves in the main-line far from the 1st ply ? >> >> >> >>(BTW: fritz5.32 behaves the same way. it works the >>same way, using heavy preprocessing methods.) >> >>Fritz5 and Fritz6 are strong programs. >>When you let them play against humans or against >>other chess programs. They are not the strongest >>chess programs (ChessTiger and others are much stronger) >>but they are much for the money they cost. >> >>But - as an analysis tool for chess players... >>NO ! >> >> >>i would like to see all my opponents use this type of programs >>(nimzo, junior...) >>so that i can easily beat them. >This does not surprise me at all. I've seen this happens with other engines as >well. I don't think it is fair to pick on Fritz and accuse it that it's stupid >in analysis or it's very dumb, but the user behind it. It's like the old >saying, the blind leads the blind and they both fall off into the ditch. >Therefore, this is a warning sign to all users who relies solely and takes any >computer chess analysis as the ULTIMATE truth. I personally never take any chess >analysis to its face value, I always play another move, or another ply and see >if the evaluation changes dramatically. If it remains the same, then I know that >the assessment is correct, if it changes dramatically, then it's because of the >horizon effect which all chess engines suffer, No,it is not the horizon effect It is the fact that Fritz is a root processor. cxb6 was played at depth 3-13 with -1.xx evaluation after cxb6 axb3 was played at depth 4-13 and you cannot explain this by search. Uri
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