Author: Dann Corbit
Date: 17:49:56 08/02/99
Go up one level in this thread
On August 02, 1999 at 20:06:07, Ricardo Gibert wrote: >On August 02, 1999 at 18:15:27, Jeff Anderson wrote: > >>Could someone with access to the KQ v kr endgame tablebase tell me how many >>moves before Black mates in this position? > >I believe the tablebases are not optimized for finding the shortest mate. For >instance, in this case, it finds the shortest route to mate OR win the rook. >After winning the rook, it then finds the shortest mate from there. So it is >possible the "best" play generated by the table base is not the shortest mate. >It is also possible for a tablebase, organized differently, can give a solution >of a different length than another tablebase, though I would not expect that >here. > >So "perfection" is not guaranteed, but it does have the virtue of being optimal >in the light of the 50 move rule. In other words, it is possible that a position >is winnable without exceeding the 50 move rule, but the "shortest mate" would >exceed the 50 move rule. Of course, in that case it would not really be the >"shortest mate." I would be interested in seeing an example position of this if >someone has it. The Nalimov tablebase files have distance to mate. But as a confirmation, here is the output of Chest: Reading job: W: Kg2 Rf2 (2) B: Kg4 Qa2 (2) FEN: 8/8/8/8/6k1/8/q4RK1/8 b - - analysing (mate in 14 moves): No solution in 14 moves. refu 1: Qa8+ Kf1 [ 13-] solu 1: Rf3 [ 4+] solu 2: Kh2 [ 12+] solu 3: Kg1 [ 10+] refu 2: Qd5+ Kf1 [ 13-] solu 4: Rf3 [ 4+] solu 5: Kg1 [ 4+] solu 6: Kh2 [ 13+] refu 3: Qa3 Kg1 [ 13-] solu 7: Rd2 [ 5+] solu 8: Rc2 [ 11+] solu 9: Rf6 [ 12+] solu 10: Rf4+ [ 4+] solu 11: Rf7 [ 13+] solu 12: Rf1 [ 8+] solu 13: Kh2 [ 5+] solu 14: Rf5 [ 6+] solu 15: Rf3 [ 4+] solu 16: Rf8 [ 4+] solu 17: Re2 [ 4+] refu 4: Qa4 Rd2 [ 13-] solu 18: Rf6 [ 11+] solu 19: Rf7 [ 12+] solu 20: Rf8 [ 13+] refu 5: Qa5 Re2 [ 13-] solu 21: Rf4+ [ 4+] solu 22: Rc2 [ 12+] solu 23: Rf6 [ 11+] solu 24: Rf7 [ 7+] solu 25: Rf1 [ 6+] solu 26: Rf8 [ 13+] solu 27: Rb2 [ 11+] solu 28: Rf3 [ 4+] solu 29: Kh2 [ 12+] solu 30: Rf5 [ 4+] refu 6: Qa6 Rd2 [ 13-] solu 31: Rf4+ [ 4+] solu 32: Re2 [ 3+] refu 7: Qa7 Rc2 [ 13-] solu 33: Rf4+ [ 4+] solu 34: Kg1 [ 3+] refu 8: Qa1 Rf8 [ 13-] solu 35: Rf4+ [ 4+] solu 36: Rf6 [ 4+] solu 37: Rb2 [ 3+] refu 9: Qb3 Kg1 [ 13-] solu 38: Rf4+ [ 4+] solu 39: Rd2 [ 5+] solu 40: Rf6 [ 11+] solu 41: Rf5 [ 5+] solu 42: Ra2 [ 3+] solu 43: Rf8 [ 13+] solu 44: Rf1 [ 6+] solu 45: Kh2 [ 5+] solu 46: Rf3 [ 4+] solu 47: Rf7 [ 4+] solu 48: Re2 [ 4+] refu 10: Qc4 Rd2 [ 13-] solu 49: Rf6 [ 11+] solu 50: Rf4+ [ 3+] solu 51: Rf5 [ 6+] solu 52: Rf3 [ 4+] solu 53: Rf7 [ 4+] solu 54: Rf1 [ 6+] solu 55: Re2 [ 3+] solu 56: Rc2 [ 3+] solu 57: Ra2 [ 3+] solu 58: Rf8 [ 13+] refu 11: Qe6 Rd2 [ 13-] solu 59: Rf4+ [ 4+] refu 12: Qg8 Rd2 [ 13-] solu 60: Rf4+ [ 4+] solu 61: Rf3 [ 4+] refu 13: Qb1 Rf8 [ 13-] solu 62: Rf4+ [ 4+] solu 63: Rf7 [ 12+] solu 64: Rf6 [ 11+] solu 65: Rf5 [ 4+] solu 66: Rc2 [ 3+] solu 67: Ra2 [ 3+] Time (user) = 856.00 sec (ca. 14.3 min)
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