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Subject: Re: Mate in 46

Author: Enrique Irazoqui

Date: 10:23:43 02/02/01

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On February 02, 2001 at 12:58:53, Heiner Marxen wrote:

>On February 02, 2001 at 08:40:06, Enrique Irazoqui wrote:
>
>>On February 02, 2001 at 07:47:52, Heiner Marxen wrote:
>>
>>>On February 01, 2001 at 17:47:23, Ignacio Santos Crespo wrote:
>>>
>>>>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
>>>>>>>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
>>>>(6´2")
>>>
>>>While I'm pleased to hear that a program solved this one,  from the above
>>>I believe "mate in 44" would be correct, not "mate in 42".  Can you show
>>>us a PV?  I would like to check it.  Someone errs, and I'd like to know who.
>>>
>>>Heiner
>>
>>Junior 6 says mate in 42 after 2... Bg6+ in 55 seconds on a P750, 128MB hash,
>>see below. I find very impressive that a playing program can see so far ahead
>>and so quickly. I'm trying from the initial position with Deep Junior, but after
>>14 hours it doesn't see the mate yet.
>
>Hmm, maybe because there are some #7 side variants?  E.g. after 1.gxf3
>Qxf6+ Nxf6+  Kc6   Rc4+   Kb7   Nd6+   =*=   f8=Q+  Re8   Qxe8+  Bc8  Qxc8#

Maybe. I gave up after 18 hours.

>>Enrique
>>
>>[D]2N5/p4P2/p4RbP/P2kr2K/5RN1/2PPBPP1/3P1p2/5Q2 w - - 0 1
>>
>>Analysis by Junior 6.0:
>[snip]
>>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
>>  +-  (#42)   Depth: 44   00:00:55  40825kN
>>
>>(Irazoqui, Cadaqués 02.02.2001)
>
>The above line follows exactly my PV from above.  Unfortunately Juniors PV
>is not complete, so I cannot investigate this further.  But when Chest is
>right with #46, then Junior should have said #44 (or larger), but not #42.
>That would be a bug, wouldn't it?
>
>OTOH, Chest may have the bug, which is what worries me a bit.
>Would you mind to provide the complete line up to the mate move?
>You could play it out after the above analysis.  Thanks in advance!

Sorry, I can't right now. Maybe in a few days I'll have the time to try.

Enrique

>BTW, I spent some 5 minutes for Crafty analysis, but it appears to not solve
>it: it did reach depth 14, only.
>
>Heiner



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