Author: Heiner Marxen
Date: 15:18:55 01/31/01
Go up one level in this thread
On January 31, 2001 at 17:54:13, Dann Corbit 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. > >4 seconds on my machine. I made this change: > >#ifndef MAX_ANA_DEPTH ># define MAX_ANA_DEPTH ((255 >> 2)-1) /* CF: maximum depth (a 2 moves) of >analysis */ >#endif Perfect! >can MAX_ANA_DEPTH be increased further without major surgery? I don't know, offhand. I have to look deeper. There could be problems... Just now it would not compile, because ANA_MANY should be at least as large, which together with two more bits shall fit into a single byte in the TT... well, "major surgery" will be needed. >2N5/p4P2/p4RqP/P2krb2/5RNK/2PPBnP1/3P1pP1/5Q2 w - - acn 571764; acs 4; bm gxf3; >ce 32676; dm 46; pv gxf3 Qh5+ Kxh5 Bg6+ Kxg6 Rg5+ Kh7 Rg7+ Kh8 Rh7+ Kg8 Rh8+ Kg7 >Rh7+ Kf8 Rh8+ Ke7 Re8+ Kd7 Rd8+ Kc7 Rd7+ Kb8 Rb7+ Ka8 Rb8+ Kxa7 Rb7+ Kxa6 Ra7+ >Kb5 Rxa5+ Kb4 Rb5+ Ka3 Rb3+ Ka2 Rb2+ Ka1 Ra2+ Kb1 Rb2+ Kc1 Rb1+ Kc2 Rb2+ Kd1 >Rb1+ Ke2 Re1+ Kxf2 Re2+ Kg1 Rg2+ Kh1 Rg1+ Kh2 Rh1+ Kg2 Rg1+ Kh3 Rxg3+ Kh4 Rh3+ >Kg5 Rh5+ Kg6 Rg5+ Kh7 Rg7+ Kh8 Rh7+ Kg8 Rh8+ Kg7 Rh7+ Kg6 Rg7+ Kh5 Rg5+ Kh4 Rh5+ >Kg3 Rh3+ Kf2 Rxf3+ Ke2 Rxe3+ Nxe3+ Ke5 d4#; Amazing! :-O Heiner
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