Author: Dann Corbit

Date: 14:54:13 01/31/01

Go up one level in this thread

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 can MAX_ANA_DEPTH be increased further without major surgery? 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#;

- Re: Mate in 46
**Heiner Marxen***15:18:55 01/31/01*

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