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Subject: Re: Mate in 46

Author: Ignacio Santos Crespo

Date: 14:47:23 02/01/01

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On January 31, 2001 at 11:25:25, Enrique Irazoqui wrote:

>On January 31, 2001 at 10:25:50, Heiner Marxen wrote:
>
>>On January 30, 2001 at 17:15:45, Olaf Jenkner wrote:
>>
>>>Perhaps I had in mind this problem what is easily to prove that there is
>>>no shorter mate.
>>>
>>>Pervakow/Sum.  #46
>>>[D]2N5/p4P2/p4RqP/P2krb2/5RNK/2PPBnP1/3P1pP1/5Q2 w - - 1 0
>>
>>Yes, that can be.  Much to my own surprise Chest really proves this
>>as a mate in 46 moves, and needs just 8.2 seconds (K7/600) for it.
>>It gives the following PV:
>>
>> 1. gxf3  Qh5+
>> 2. Kxh5  Bg6+
>> 3. Kxg6  Rg5+
>> 4. Kh7   Rg7+
>> 5. Kh8   Rh7+
>> 6. Kg8   Rh8+
>> 7. Kg7   Rh7+
>> 8. Kf8   Rh8+
>> 9. Ke7   Re8+
>>10. Kd7   Rd8+
>>11. Kc7   Rd7+
>>12. Kb8   Rb7+
>>13. Ka8   Rb8+
>>14. Kxa7  Rb7+
>>15. Kxa6  Ra7+
>>16. Kb5   Rxa5+
>>17. Kb4   Rb5+
>>18. Ka3   Rb3+
>>19. Ka2   Rb2+
>>20. Ka1   Ra2+
>>21. Kb1   Rb2+
>>22. Kc1   Rb1+
>>23. Kc2   Rb2+
>>24. Kd1   Rb1+
>>25. Ke2   Re1+
>>26. Kxf2  Re2+
>>27. Kg1   Rg2+
>>28. Kh1   Rg1+
>>29. Kh2   Rh1+
>>30. Kg2   Rg1+
>>31. Kh3   Rxg3+
>>32. Kh4   Rh3+
>>33. Kg5   Rh5+
>>34. Kg6   Rg5+
>>35. Kh7   Rg7+
>>36. Kh8   Rh7+
>>37. Kg8   Rh8+
>>38. Kg7   Rh7+
>>39. Kg6   Rg7+
>>40. Kh5   Rg5+
>>41. Kh4   Rh5+
>>42. Kg3   Rh3+
>>43. Kf2   Rxf3+
>>44. Ke2   Rf2+
>>45. Nxf2  Ke5
>>46. R4f5#
>>
>>I even had to increase the maximal allowed depth in Chest (formerly 30).
>>Quite an exceptional position!
>>
>>Can the playing programs solve this, also?  I suspect so.
>
>92 plies? You must be kidding. They pick gxf3 instantly with a huge score, but
>no mate. I only tried Deep Fritz, Gambit Tiger and Shredder 5, but I don't think
>any playing program will see it.
>
>Enrique
>
>>Heiner

On my Pentium 166 after 2... Bg6+, Junior 6 (with 15 Mb. hash) say mate in 42
(62")



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