Computer Chess Club Archives




Subject: Re: Mate in 38.

Author: Paul

Date: 00:38:51 01/26/01

Go up one level in this thread

On January 25, 2001 at 22:18:42, Uri Blass wrote:

>On January 25, 2001 at 20:04:20, Paul wrote:
>>On January 25, 2001 at 20:02:19, Dann Corbit wrote:
>>>On January 25, 2001 at 19:40:58, Paul wrote:
>>>>On January 24, 2001 at 19:39:52, Dan Andersson wrote:
>>>>>[D]1R6/6pK/5p2/4p3/1B1p3n/8/p1p1pp2/1k3b2 w - - 0 1
>>>>>Krabbé (1985)
>>>>I just tried this position with my program Pretz, after having unsuccesfully
>>>>grappled with the mate in 16/20 positions by José Antônio Fabiano Mendes
>>>>(I ran out of patience :) and indeed get a mate in 38! It's amazing!
>>>>02:17 WM38 09 1. Ba3+ Ka1 2. Bb2+ Kb1 3. Bxd4+ Kc1 4. Be3+ Kd1 5. Rd8+ Ke1 6.
>>>>Bd2+ Kd1 7. Bb4+ Kc1 8. Ba3+ Kb1 9. Rb8+ Ka1 10. Bb2+ Kb1 11. Bxe5+ Kc1 12. Bf4+
>>>>Kd1 13. Rd8+ Ke1 14. Bd2+ Kd1 15. Bb4+ Kc1 16. Ba3+ Kb1 17. Rb8+ Ka1 18. Bb2+
>>>>Kb1 19. Bxf6+ Kc1 20. Bg5+ Kd1 21. Rd8+ Ke1 22. Bd2+ Kd1 23. Bb4+ Kc1 24. Ba3+
>>>>Kb1 25. Rb8+ Ka1 26. Bb2+ Kb1 27. Bxg7+ Kc1 28. Bh6+ Kd1 29. Rd8+ Ke1 30. Bd2+
>>>>Kd1 31. Bb4+ Kc1 32. Ba3+ Kb1 33. Rb8+ Ka1 34. Be7 c1=Q 35. Bf6+ Qb2 36. Rxb2
>>>>e1=Q 37. Rb8+ Qe5 38. Bxe5x
>>>>I used 96MB hash and full ply extensions on check and one-rep, and some
>>>>other tricks :) Does this look ok? Has anyone else tried this position?
>>>You solve that in 2:18?!
>>>That is pretty amazing.
>>Just found out that it isn't too amazing ... even without tricks, just
>>extending full plies on one-rep and check works! Same time! So I guess
>>every program should find this :)
>Most programs avoid extending full plies for checks so they cannot find it.
>I guess that extending full plies for check is not productive for games and that
>there are position when you cannot complete depth1 or 2 in a reasonable time.

That's true. But my remark was directed at the programmers, not users.
Program authors can tweak their engine settings to extend more just to
solve this one problem. That's why I mentioned the settings I used, they
are not my 'defaults' either. And it would be nice to have a verification.

>A lot of programs also do not have the single reply extension.

Don't know about that!


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