Author: Heiner Marxen
Date: 09:58:53 02/02/01
Go up one level in this thread
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# >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! 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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