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Subject: Re: Position from yesterday, Rxc7!!, problem for all Rybka versions.

Author: Terry McCracken

Date: 13:40:28 02/09/06

On February 09, 2006 at 13:00:39, Andreas St. wrote:

>Hi,
>yesterday i posted this position:
>
>[D]2r5/2pR1pk1/p1P3p1/P2K4/5P1p/5P1P/8/8 w - - 0 1
>
>and some users said, Rybka finds the solution.
>
>>Not Rybka 13b, but Rybka 1.0 Beta 32-bit (the first version!!!)
>>Best regards,
>>Orlando
>
>>Rybka 1.0 Beta 32-bit, sees Rxc7 quickly. I've no idea how the person testing
>>whatever version had this failure.
>
>>Terry
>
>
>What do you mean??? No Rybka version finds the only winning move Rxc7!
>If you analyse long enough, you will see, all Rybka versions prefers f5.
>At the latest after one hour no Rxc7, but f5!
>And look at the score of rybka. He sees nothing in this position.
>Fritz 9 for example has +3.50 after 42sec.
>Shredder 9 after 0 sec.! After 17sec. Score +3.05

I didn't let it run and run to see if it changes its tune.
It has to be some kind of glich.
>
>Mephisto Vancouver finds the correct move in 8min 45sec!
>Fritz, Junior, Shredder.... have no problems to find the correct move Rxc7 with
>a high score about +4:
>
>Here a winning line (white wins quickly):
>
>1.Rxc7!! Rxc7 2.Kd6 Rc8 3.Kd7 Rh8 4.c7 Kf6 5. c8Q Rxc8 6.Kxc8 and white wins!

I know the winning line, it's very simple. After the Rooks are exchanged White
picks up the a6 pawn and Queens on the a-file with it's a5 pawn much faster than
Black can, so Black is lost.


>
>
>Here an analysis of Rybka (all Pentium IV, 3,28 GHZ, 256MB hash)
>Rybka 1.0 Beta 32-bit:
>
>1.Kd4 Kf6 2.Kc4 Ke6 3.Kc5 Kf6 4.Kd4
>  ²  (0.32)   Tiefe: 10   00:00:00  11kN
>1.Kd4 Kf6 2.Kc4 Ke6 3.Kc5 Kf6 4.Kd4 Ke6
>  =  (0.15)   Tiefe: 11   00:00:00  25kN
>1.Kd4 Kf6 2.Kc4 Ke6 3.Kc5 Kf6 4.Kd4 Ke6 5.Kc4 Kf6
>  =  (0.25)   Tiefe: 12   00:00:00  41kN
>1.Kd4 Kf6 2.Kc4 Ke6 3.Kc5 Kf6 4.Kd4 Ke6 5.Kc4 Kf6
>  =  (0.18)   Tiefe: 13   00:00:00  63kN
>1.Kd4 Kf6 2.Kc4 Ke6 3.Kd3 Kf6 4.Kd4 Ke6 5.Kc4 Kf6
>  =  (0.18)   Tiefe: 14   00:00:00  150kN
>1.Kd4 Kf6 2.Kc4 Ke6 3.Kd3 Kf6 4.Kd4 Ke6 5.Kc4 Kf6
>  =  (0.19)   Tiefe: 15   00:00:00  217kN
>1.Kd4 Kf6 2.Kc5 Ke6 3.Kc4 Kf6 4.Kd3 Ke6 5.Ke4 Kf6
>  =  (0.09)   Tiefe: 16   00:00:02  594kN
>1.Kd4 Kf6 2.Kc5 Ke6 3.Kc4 Kf6 4.Kd3 Ke6 5.Ke4 Kf6
>  =  (0.09)   Tiefe: 17   00:00:02  793kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.c7 Kf6 4.Kd7 Th8 5.c8D Txc8
>  ±  (0.93)   Tiefe: 17   00:00:03  1333kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.c7 Kf6 4.Kd7 Th8 5.c8D Txc8
>  ±  (1.00)   Tiefe: 18   00:00:03  1580kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.c7 Kf6 4.Kd7 Th8 5.c8D Txc8
>  ±  (0.88)   Tiefe: 19   00:00:04  1789kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.c7 Kf6 4.Kd7 Txc7+ 5.Kxc7 Ke6
>  ±  (1.04)   Tiefe: 20   00:00:06  2980kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.Kd7 Ta8 4.c7 Kf8 5.c8D+ Txc8
>  ±  (1.04)   Tiefe: 21   00:00:08  3828kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.Kd7 Ta8 4.c7 Kf8 5.c8D+ Txc8
>  ±  (0.97)   Tiefe: 22   00:00:12  4906kN
>1.f5 g5 2.Txc7 Txc7 3.Kd6 Tc8 4.c7 Kf6 5.Kd7 Th8
>  ±  (1.28)   Tiefe: 22   00:01:18  22266kN
>1.f5 g5 2.Txc7 Txc7 3.Kd6 Tc8 4.c7 Kf6 5.Kd7 Th8
>  ±  (1.39)   Tiefe: 23   00:01:45  27645kN
>1.f5 g5 2.Ke5 Te8+ 3.Kd4 Tc8 4.Ke3 Te8+ 5.Kf2 Kf6
>  ±  (1.04)   Tiefe: 24   00:03:53  49182kN
>1.f5 g5 2.Ke5 Te8+ 3.Kd4 Tc8 4.Ke3 Te8+ 5.Kf2 Kf6
>  ±  (0.90)   Tiefe: 25   00:05:21  64774kN
>1.f5 g5 2.Ke5 Te8+ 3.Kd4 Tc8 4.Ke3 Te8+ 5.Kd3 Tc8
>  ±  (0.87)   Tiefe: 26   00:10:04  113829kN
>1.f5 g5 2.Ke5 Te8+ 3.Kd4 Tc8 4.Ke3 Te8+ 5.Kf2 Kf6
>  ±  (0.88)   Tiefe: 27   00:23:52  228381kN
>1.f5 g5 2.Ke5 Te8+ 3.Kd4 Tc8 4.Ke3 Te8+ 5.Kf2 Kf6
>  ±  (0.84)   Tiefe: 28   00:35:36  318508kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.Kd7 Ta8 4.c7 Kf8 5.c8D+ Txc8
>  ±  (0.94)   Tiefe: 28   00:41:48  468953kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.Kd7 Ta8 4.c7 Kf8 5.c8D+ Txc8
>  ±  (0.88)   Tiefe: 29   00:47:24  555387kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.Kd7 Ta8 4.c7 Kf8 5.c8D+ Txc8
>  ±  (0.88)   Tiefe: 30   01:06:30  757475kN
>1.Txc7 Txc7 2.Kd6 Tc8
>  ±  (1.03)   Tiefe: 31   01:31:05  1042592kN
>1.Txc7 Txc7 2.Kd6 Tc8
>  +-  (1.47)   Tiefe: 32   02:32:48  1626426kN
>1.Txc7 Txc7 2.Kd6 Tc8 3.Kd7
>  +-  (1.49)   Tiefe: 33   04:45:24  2788067kN
>
>Rybka finds Rxc7 the best after 41 min, but only with a score +0.94.
>So he don't see a win!
>I aborted with Rybka 13b after one hour, he wants f5.

For a human the win is elementary. Computers don't "understand" and have to
search to great depths.

Terry

Is black really lost for sure??????!!!!!!!! Bernardo Wesler 15:27:10 02/09/06
- Re: Is black really lost for sure??????!!!!!!!! Terry McCracken 15:53:21 02/09/06
  - Re: Is black really lost for sure??????!!!!!!!! Mark Ryan 16:31:37 02/09/06
    - Re: Is black really lost for sure??????!!!!!!!! Terry McCracken 20:53:24 02/09/06
Re: Position from yesterday, Rxc7!!, problem for all Rybka versions. Steve Maughan 14:03:15 02/09/06
- Re: Position from yesterday, Rxc7!!, problem for all Rybka versions. Terry McCracken 15:37:59 02/09/06
  - Re: Position from yesterday, Rxc7!!, problem for all Rybka versions. Steve Maughan 16:41:26 02/09/06
    - Re: Position from yesterday, Rxc7!!, problem for all Rybka versions. Mark Ryan 17:02:55 02/09/06
      - Re: Position from yesterday, Rxc7!!, problem for all Rybka versions. Steve Maughan 17:27:02 02/09/06
      - Re: Position from yesterday, Rxc7!!, problem for all Rybka versions. Robin Smith 17:24:32 02/09/06
        
        Re: Position from yesterday, Rxc7!!, problem for all Rybka versions. Terry McCracken 20:51:11 02/09/06
        
        Re: Thanks. Mark Ryan 17:37:39 02/09/06

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