Author: Uri Blass
Date: 01:36:13 03/24/03
Go up one level in this thread
On March 24, 2003 at 04:32:04, Uri Blass wrote:
>On March 24, 2003 at 04:15:45, Uri Blass wrote:
>
>>On March 24, 2003 at 03:19:41, Will Singleton wrote:
>>
>>>On March 24, 2003 at 02:52:40, Will Singleton wrote:
>>>
>>>>On March 24, 2003 at 02:25:33, Bernhard Bauer wrote:
>>>>
>>>>>On March 24, 2003 at 02:07:31, Will Singleton wrote:
>>>>>
>>>>>>Position from Baron – Amateur bm Qxc2
>>>>>>[D]2rr3k/pb3ppp/4p3/4P3/1n1B3R/1P4P1/P1q4P/1Q1RKB2 w - - 0 30
>>>>>>
>>>>>>For some reason, Ruffian and Crafty have a very tough time with this one. I
>>>>>>wonder whether this could be due to some similarity between them.
>>
>>By this logic public movei that probably need more time on your machine is also
>>similiar to Crafty.
>>
>>
>>I think that a lot of engines are slower than Ruffian(probably most of the free
>>engines).
>>
>> A problem in
>>>>>>repetition detection, perhaps? On my machine, amd 1.6ghz:
>>>>>>
>>>>>> Fail-low solution
>>>>>>Yace 0:15 0:20
>>>>>>CM 0:15 0:30
>>>>>>Shredder 0:35 0:45
>>>>>>Amateur 0:20 0:50
>>>>>>Ruffian 2:34 3:54
>>>>>>Crafty 5:42 > 9 minutes
>>>>>>
>>>>>>---------------------------------
>>>>>>[Event "Computer chess game"]
>>>>>>[Site "MICRON"]
>>>>>>[Date "2003.03.23"]
>>>>>>[Round "1"]
>>>>>>[White "The Baron 0.99.5a"]
>>>>>>[Black "Amateur 2.44"]
>>>>>>[Result "0-1"]
>>>>>>[TimeControl "40/600"]
>>>>>>
>>>>>>1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. g3 Be7 5. Bg2 O-O 6. Qc2 c6 7. O-O Nbd7 8.
>>>>>>Nbd2 b6 9. e4 Bb7 10. e5 Ne8 11. b3 Rc8 12. Bb2 c5 13. Rac1 cxd4 14. Nxd4
>>>>>>Kh8 15. Rfe1 Nc7 16. cxd5 Nxd5 17. Qb1 Nc5 18. Red1 Qd7 19. Ne4 Rfd8 20.
>>>>>>Ne2 Qb5 21. Nd4 Qa6 22. Nxc5 Bxc5 23. Bf1 Qa5 24. Rc4 b5 25. Nxb5 Qxb5 26.
>>>>>>Rh4 Bxf2+ 27. Kxf2 Qc5+ 28. Bd4 Qc2+ 29. Ke1 Nb4 30. Bxa7 Qc3+ 31. Kf2 Qf3+
>>>>>>32. Kg1 Qh1+ 33. Kf2 Qf3+ 34. Kg1 h5 35. Rd6 g5 36. Rh3 Rxd6 37. exd6 Rc2
>>>>>>38. Qxc2 Nxc2 39. d7 Qd5 40. Bb6 Qxd7 41. Rxh5+ Kg7 42. Rxg5+ Kf6 43. Rb5
>>>>>>Qd1 44. a3 Bc6 45. Rb4 Nxb4 46. g4 Nd3 47. Bd4+ Ke7 48. Bc5+ Nxc5 49. h4
>>>>>>{Baron resigns} 0-1
>>>>>
>>>>>Crafty 19.3 needs 28 sec on an AMD 1,8 GHz. So I can't see a very tough time.
>>>>>Regards
>>>>>Bernhard
>>>>
>>>>Very interesting. I was using Crafty 19.1. I just ran the position on 19.2 and
>>>>19.3, confirming your results with 19.3. 19.2, however, behaves likes 19.1,
>>>>taking several minutes. I'm off to check the source changes.
>>>>
>>>
>>>More interesting. 19.3 has rewritten the repetition code. As I pointed out in
>>>the original post, a problem with repetition detection might cause difficulty
>>>with this position. What do you know.
>>>
>>>Will
>>
>>I do not understand what it has to do with repetition
>>
>>Movei0.0799 has problems in this position when Movei0.08031 can find it clearly
>>faster(slightly more than 2 minutes on p850 for 0.08031 and more than 20 minutes
>>for 0.0799 but I did not save exact solution times and it is not important
>>because I did other things during the analysis but not things that made the
>>program significantly slower based on looking at the nps).
>>
>>I did not change repetition detection code but I added evaluation
>>of king safety and did a lot of other changes in the search.
>>
>>I do not see what repetition has to do with it because the evaluation is
>>negative before the fail low and after the fail low(with king safety evaluation
>>it is easier to find Qxc2 because with king safety evaluation it is clear that
>>white need to trade queeens to prevent problems with king safety).
>>
>>Can you give the repetition line that give problems to programs to see the fail
>>low?
>>
>>Uri
>
>
>I can add that the main problem is null move pruning.
>It is not easy to see the threat
>after a line like Bxa7 Qc3+ Kf2 Qf3+ Kg1 h6
>
>King safety evaluation may help not to prune the wrong lines and I guess that
>minimal king safety evaluation is the reason that latest movei can find it
>relatively faster(not as fast as amateur but at least significantly faster than
>ruffian).
>
>Uri
I think that more moves needed to be added after h6 because the threat Rxd1 is
obvious.
Probably after
Bxa7 Qc3+ Kf2 Qf3+ Kg1 h6 Rxd8 Rxd8 the threat is not so obvious without good
king safety evaluation.
Uri
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