Author: Robert Hyatt
Date: 19:07:05 02/08/03
Go up one level in this thread
On February 08, 2003 at 11:06:46, Dieter Buerssner wrote:
>On February 08, 2003 at 00:04:10, Robert Hyatt wrote:
>
>>>8/8/8/6Np/2N5/Pk6/6K1/8 w - a3
>
>>A4 leads to a mate in 91 as the best black can do, according to
>>the same "authority". However, it would require a close inspection
>>to be sure it won't go past the 50 move rule...
>
>Would you have any idea, how you could inspect this with available means (say
>Nalimov or Thompson TBs). This is the line I get:
>
>
> 636128 1.748 -Mat91 9t 1...Kxa4 {EGTB} 2. Nd2 h4 3. Nh3!! Kb4 4. Kf3!
> Kb5 5. Ke4! Kc6! 6. Kd4! Kd6! 7. Nf3 Ke6 8.
> Kc4! Kd6 9. Nd4! Ke5! 10. Kc5! Ke4! 11. Ne6!
> Ke5 12. Neg5! Kf6! 13. Kd5 Kf5! 14. Kd4! Kf6!
> 15. Ke4! Ke7! 16. Ke5! Kd7! 17. Kd5! Kc7! 18.
> Ne4 Kb6! 19. Nd6! Ka5! 20. Kc5! Ka4! 21. Ne4!
> Kb3! 22. Kb5! Kb2! 23. Kb4! Kc2 24. Kc4! Kb2
> 25. Nd2! Ka2 26. Kb4! Kb2! 27. Nf3! Kc2! 28.
> Kc4! Kb2! 29. Nf2! Ka3! 30. Kb5! Kb3! 31. Ne4!
> Ka3 32. Nc5! Kb2! 33. Kc4!! Kc2! 34. Kd4! h3!
> 35. Nh2!! Kd2! 36. Nb3+! Kc2! 37. Kc4! Kb2! 38.
> Nd4! Ka2! 39. Kc3! Ka3! 40. Nb3! Ka4 41. Kc4!!
> Ka3 42. Nc5! Ka2 43. Kd3! Kb2 44. Kd2! Ka2 45.
> Kc2! Ka3! 46. Kc3!! Ka2 47. Nd3! Kb1! 48. Kb3!
> Ka1 49. Kc2! Ka2 50. Nb2! Ka3 51. Kc3!! Ka2 52.
> Nc4! Kb1! 53. Kd2! Ka1! 54. Kc1! Ka2 55. Kc2!!
> Ka1 56. Kb3! Kb1 57. Nd2+! Kc1! 58. Kc3! Kd1
> 59. Nb3! Ke1! 60. Kd4! Ke2! 61. Ke4! Ke1! 62.
> Ke3! Kd1 63. Kd3! Ke1 64. Nd4 Kd1! 65. Ne2! Ke1
> 66. Nc3! Kf2 67. Kd2! Kg2! 68. Ke2 Kg3! 69.
> Ke3!! Kh4! 70. Kf4!! Kh5 71. Kf5!! Kh6! 72.
> Kf6! Kh7 73. Nd5 Kg8! 74. Ke7! Kh7! 75. Kf7!!
> Kh6! 76. Kf6!! Kh7 77. Ne3 Kh6! 78. Neg4+! Kh7!
> 79. Kf7! Kh8 80. Ne3 Kh7 81. Nf5! Kh8 82. Kg6!
> Kg8 83. Ng7! Kf8! 84. Kf6!! Kg8 85. Ne6! Kh7!
> 86. Kg5! Kg8! 87. Kg6!! Kh8 88. Kf7! Kh7 89.
> Ng4! h2 90. Ng5+ Kh8 91. Ne5!! h1=Q 92. Ng6#!!
>
>It is only a "sample line", as other lines also lead to mate in the 92nd move.
>But a line, my engine could play in this position. There are over 50 moves
>between h3 and h2. So, it is not unlikely, that my engine would actually draw
>this. How can we know, that it is not a theoretical draw? I see no easy means
>without calculating different TBs.
At least the above line looks like a draw. IE h3 on move 34, then h2 on
move 89, certainly goes beyond the 50 move rule. The question is if there
is another way to play this to make black push the pawn earlier.
>
>One could try, to not allow EGTB cutoffs, when distance to mate in plies plus
>counter is > 100. But the mate is so deep, that the to search tree would need to
>be extremely slim, to ever end such a search. Also, one would of course need to
>be extremely careful with HTs.
>
>I believe Eduard Nemeth posted this position once (perhaps in a German forum).
>After Eduard's post I added a few lines of code, that makes eval scores of 2N
>and nothing else rather drawish at most.
>
>Regards,
>Dieter
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