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Subject: Re: typical: a sensation happens and nobody here registers it !

Author: Robert Hyatt

Date: 10:19:24 10/18/00

Go up one level in this thread


On October 18, 2000 at 10:43:41, Uri Blass wrote:

>On October 18, 2000 at 10:32:03, Robert Hyatt wrote:
>
>>On October 18, 2000 at 01:20:51, Christophe Theron wrote:
>>
>>>On October 17, 2000 at 17:29:04, Robert Hyatt wrote:
>>>
>>>>On October 17, 2000 at 13:09:52, Christophe Theron wrote:
>>>>
>>>>>On October 16, 2000 at 23:21:23, Robert Hyatt wrote:
>>>>>
>>>>>>On October 16, 2000 at 21:57:28, Sune Larsson wrote:
>>>>>>
>>>>>>>On October 16, 2000 at 21:10:04, Robert Hyatt wrote:
>>>>>>>
>>>>>>>>On October 16, 2000 at 19:51:41, Chessfun wrote:
>>>>>>>>
>>>>>>>>>On October 15, 2000 at 21:35:33, Robert Hyatt wrote:
>>>>>>>>>
>>>>>>>>>>I have to disagree.  It is not hard to tune my (or any other) program to
>>>>>>>>>>play this move.  If you watch gambit tiger play, it has some _outrageous_
>>>>>>>>>>scores.  In a game on ICC the other night, Crafty was at -.2, gambit tiger
>>>>>>>>>>was at +3.2...
>>>>>>>>>
>>>>>>>>>Dr. I am interested in seeing this game.
>>>>>>>>>I assume it was against subtleone as I currently see 9 in
>>>>>>>>>it's history. Can you advise which game it was.
>>>>>>>>>
>>>>>>>>>Thanks.
>>>>>>>>
>>>>>>>>
>>>>>>>>I honestly don't know.  Albert can answer as we were chatting during the
>>>>>>>>games...  he was kibitzing tiger scores, crafty was kibitzing its own scores.
>>>>>>>>
>>>>>>>>About all I can do to help is to say crafty was white, it was an opposite
>>>>>>>>castling game (crafty on queenside, tiger on the kingside).  I came in right
>>>>>>>>after the opening so I didn't notice what it was.  And due to distractions I
>>>>>>>>don't know how it ended.  I simply remembered +3.2 from tiger, and -.2 for
>>>>>>>>Crafty...  until finally Albert said something like "+.5 here now, it seems
>>>>>>>>that the attack is over..."
>>>>>>>>
>>>>>>>>Bob
>>>>>>>
>>>>>>>
>>>>>>>Maybe it was the following game:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>[Event "ICC u 5 3 2000.11.02"]
>>>>>>>[Site "Internet Chess Club"]
>>>>>>>[Date "2000.11.02"]
>>>>>>>[Round "-"]
>>>>>>>[White "crafty"]
>>>>>>>[Black "SubtleOne"]
>>>>>>>[Result "0-1"]
>>>>>>>[WhiteElo "2935"]
>>>>>>>[BlackElo "2912"]
>>>>>>>
>>>>>>>1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 d6
>>>>>>>6. Bg5 e6 7. Qd2 Be7 8. O-O-O O-O 9. Nb3 Qb6 10. f3 Rd8
>>>>>>>11. Be3 Qc7 12. Qf2 d5 13. exd5 Nxd5 14. Nxd5 Rxd5 15. Rxd5 exd5
>>>>>>>16. g4 Bf6 17. Kb1 Be6 18. c3 Rc8 19. Bxa7 Nxa7 20. Qxa7 Qf4
>>>>>>>21. Bg2 b5 22. Rc1 Qxh2 23. Qf2 Qf4 24. Qd2 Qxd2 25. Nxd2 d4
>>>>>>>26. Ne4 b4 27. a3 bxc3 28. bxc3 Be7 29. cxd4 Ba2+ 30. Kb2 Bxa3+
>>>>>>>31. Kxa3 Rxc1 32. Kxa2 Rc2+ 33. Kb3 Rxg2 34. d5 f5 35. gxf5 Kf7
>>>>>>>36. d6 h5 37. Nc5 h4 38. Ne6 Ke8 39. Nf4 Rf2 40. Kc4 Rxf3
>>>>>>>41. Ne2 h3 42. Nd4 Rf2 43. Kd3 h2 44. Ke3 Rg2 45. Kd3 h1=Q
>>>>>>>46. f6 Qd1+ 47. Kc4 Rg4 48. f7+ Kxf7 49. Kb5 Qxd4 50. d7 Qd5+
>>>>>>>51. Ka6 Qc6+ 52. Ka7 0-1
>>>>>>>
>>>>>>>I saw 5 games played 16/10 between Crafty and Gambit Tiger (SubtleOne)
>>>>>>>Result: 1-4
>>>>>>>
>>>>>>>Sune
>>>>>>
>>>>>>I don't believe that was it.  I am almost certain it was a draw,
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>Bob, getting the draw after trying a big speculative attack is not exactly what
>>>>>I would call a failure...
>>>>>
>>>>>There was no winner, but at least somebody tried something...
>>>>
>>>>
>>>>Of course it isn't...  but that was an example only.  I have seen games where
>>>>the big score turned into a lost endgame.  I only noticed that one as our
>>>>scores were over +3 _different_.
>>>
>>>
>>>
>>>But I still don't understand. It is also possible to think you are winning a
>>>knight, take it, get a +3 score, then lose the game a few moves later for any
>>>reason (checkmate, trapped queen, unstoppable passed pawn pair, whatever).
>>>
>>
>>The question would have to be "how often does that happen?"  I don't see it
>>often enough to be able to cite a single game.  The question has to be, which
>>is more prone to errors.  I would say sacrificing pieces for mythical advantages
>>is more dangerous than the case where you think you win a piece but don't,
>>because the former will happen far more often, IMHO of course.
>
>
>I believe that the choice to use gambittiger and not the default tiger suggest
>that the change in gambittiger is not wrong inspite of the fact that christophe
>did not finish to tune the evaluation.
>
>Uri

I would hardly say his approach is _wrong_.  I only said it is _suspect_ and
found a couple of cases where the evaluation itself was probably wrong, even
if the overall approach works well.

The problem here is "full width".  If you have a fast, deep searcher.  And you
have a broken piece of evaluation, such a big tree will let the program search
into many positions where the damanged code can screw up and influence the root
score in a bad way.  Something that is 90% right won't cut it.  Because that 10%
will be used so much in today's huge trees, it will definitely influence overall
results.



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