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Subject: Re: Endgame easy test position

Author: Ed Schröder

Date: 10:02:02 09/18/01

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On September 18, 2001 at 12:22:20, Robert Hyatt wrote:

>On September 18, 2001 at 10:53:39, Uri Blass wrote:
>
>>On September 18, 2001 at 10:45:15, José Carlos wrote:
>>
>>>On September 18, 2001 at 09:56:32, Ed Schröder wrote:
>>>
>>>>On September 18, 2001 at 09:40:26, Eduard Nemeth wrote:
>>>>
>>>>>First the game:
>>>>>
>>>>>[Event "TCh-YUG Herceg Novi YUG"]
>>>>>[Site "?"]
>>>>>[Date "2001.??.??"]
>>>>>[Round "?"]
>>>>>[White "Vukic,M"]
>>>>>[Black "Marinkovic,I"]
>>>>>[WhiteElo "2470"]
>>>>>[BlackElo "2440"]
>>>>>[ECO "A30"]
>>>>>[Result "1-0"]
>>>>>
>>>>>1. Nf3 Nf6 2. g3 b6 3. Bg2 Bb7 4. O-O g6 5. c4 c5 6. Nc3
>>>>>Bg7 7. d4 cxd4 8. Qxd4 d6 9. Be3 Nbd7 10. Rac1 Rc8 11. b3
>>>>>O-O 12. Qd2 Nc5 13. Rfd1 Nce4 14. Nxe4 Nxe4 15. Qe1 Qd7
>>>>>16. Nd4 Nf6 17. Nf3 Ne4 18. Qb4 Nc3 19. Rd2 Ne4 20. Rd3 Nc5
>>>>>21. Rdd1 Rfd8 22. Ne1 h5 23. Bxc5 Rxc5 24. Nd3 Bxg2
>>>>>25. Kxg2 Qb7+ 26. f3 Rc7 27. Nf2 Rdc8 28. Qd2 b5 29. cxb5
>>>>>Qxb5 30. Kf1 Bc3 31. Qd3 Qa5 32. Rc2 Bf6 33. Rdc1 Rxc2
>>>>>34. Rxc2 Rxc2 35. Qxc2 d5 36. e3 Kg7 37. Nd3 e6 38. Ke2 Qa3
>>>>>39. f4 Kg8 40. h3 Kg7 41. Kf3 Qd6 42. g4 hxg4+ 43. hxg4 e5
>>>>>44. fxe5 Bxe5 45. Nxe5 Qxe5 46. Qc5 Qf6+ 47. Kg3 Qe5+
>>>>>48. Kh3 a6 49. Qd4 Kf6 50. b4 Ke6 51. a4 Qc7 52. g5 Qc2
>>>>>53. Qf6+ Kd7 54. Qxf7+ Kd6 55. Qf6+ Kd7 56. Qd4 Ke6 57. Kg3
>>>>>Qb1 58. Qb6+ Ke7 59. Qb7+ Kf8 60. Qxd5 Qxb4 61. Qd8+ Kg7
>>>>>62. Qd4+ 1-0
>>>>>
>>>>>Position after move 61. Kg7:
>>>>>
>>>>>[D]3Q4/6k1/p5p1/6P1/Pq6/4P1K1/8/8 w - -
>>>>>
>>>>>After 62. Qf6+ is the win not easy. But after 62. Qd4+ is the game easy to win,
>>>>>and the game end! For any programs ist the move Qd4+ not easy to find.
>>>>>
>>>>>:-(
>>>>
>>>>
>>>>I am sure all Rebel programs find this instantly. A simple chess rule says:
>>>>"one pawn up in a pawn ending wins".
>>>>
>>>>Ed
>>>
>>>  Are you serious Ed? In this position, it's a clear win, but in most pawn
>>>endgames, you have to calculate a lot, or otherwise know some rules (which names
>>>I don't know how to translate from spanish to english) to figure if it's a win
>>>or not.
>>>
>>>  Maybe you were simply joking, and I didn't catch it... :)
>>
>>In most pawn endgames one pawn advantage is enough to win the game.
>>It is not something that always happens but computer can safely evaluate
>>+2 for positions with one pawn advnatage if they do not see a positional
>>advantage for the side that has less pawns.
>>
>>Uri
>
>
>I believe that if humans discover this "rule" in Rebel, it will die a slow
>and painful death on ICC.  I can create _many_ positions where the rule is
>wrong.  And if I can do it, GMs will do it.  Happened to me many times.  I
>was burned by going into simple king and pawn endings where I was a pawn up,
>but my opponent had a distant majority.  And he would win.  And win.


The rule is valid for 90% of all positions and if not search will handle
the remaining 10% close to zero. I don't give a +5 score for being a pawn
up in a pawn ending but a reasonable score update enough to force a
knight/bishop/rook/queen ending to a won pawn ending or to avoid to enter
a lost pawn ending position. The rule in Rebel is there for more than 10-12
years and in that time I have seen only one exception.

Ed




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