Author: Heiner Marxen
Date: 15:10:40 01/31/01
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On January 31, 2001 at 16:08:26, Paul 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. > >Hey, congrats!! How does that feel? ... great doesn't it :) Yes, great! :-) :-) I'm still a bit puzzeled, though. When I find the time, I will look at the search tree in more detail. >>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# > >Very funny line! > >>I even had to increase the maximal allowed depth in Chest (formerly 30). >>Quite an exceptional position! > >I also increased my maxdepth to 256 plies before trying the Mate in 120 one :) >But alas ... it didn't work. You can solve this one probably because it's a >short mate everytime the Rook stops checking? Yes: c4# or Nb6# normally. >>Can the playing programs solve this, also? I suspect so. > >I don't think so ... mine doesn't, anyway. Not that that says anything :) > >Maybe a singular extension program like Ferret could succeed; I think full ply >se's might just do it. Would give it a try myself, but don't have them (yet)! Hmm, when there is a direct mate in one, there is not much sense in searching any other move deeper than one ply, I would think. If Chest can span that tree, others should be able to do it, also. I suspect that a 1-ply mate does not stop them from searching alternatives. But it could, right? Ah, yes, Chest always does internal iterative deepening. That helps, of course. That is not very expensive for Chest, since its TT cuts most of it off. >Also maybe the position after the 3rd White or Black move, when the Crazy Rook >starts checking is doable within a week or so ... I see the first 23 ply of the >pv on my screen and that looks promising ;) > >Groetjes, >Paul Hmm, that could be fun ;-) Regards, Heiner
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