Author: Uri Blass
Date: 13:25:19 12/30/02
Go up one level in this thread
On December 30, 2002 at 15:41:49, Dieter Buerssner wrote:
>On December 30, 2002 at 15:08:22, Heiner Marxen wrote:
>
>>>>>>>>>b2r2kr/p1pqb1p1/1p5p/4p3/2P1N1P1/1P2Q3/P3P2P/4KRR1 b - - 0 1
>
>>>>>>>Perhaps Chest can prove a mate after
>>>>>>>
>>>>>>>1...Bh4+ 2. Rg3 Qd1+ 3. Kf2 Rf8+ 4. Qf3 Qd4+ 5. Kg2
>>>>>>>
>>>>>>>(After 5. Ke1 it is mate in 10 or faster, so this should also be possible?)
>>Your analysis matches the output of Chest. Here is its PV
>>
>>PV: Bxe4 c5 h5 h3 Bxf3+ Rfxf3 Bxg3 Rxf8+ Kxf8 Kxg3 Qf4+ Kg2 hxg4 h4 Rxh4 e3 Rh2+
>>Kg1 Qf2#
>>
>>In the refutation table we have:
>
>Which I don't understand, yet - but I will read it up ...
>
>>refu 19: Bxe4 c5 [ 8-]
>>solu 1: Qxe4 [ 7+]
>[...]
>
>>i.e. any of a3, a4, b4 and c5 yields the same result, and there is nothing
>>better. Kh3 and Rf2 are equally good (or bad).
>>Chest could have picked any of these instead of c5 for its PV.
>
>Nice to read this. I came to identical conclusions, but could not prove, that it
>is the shortest mate.
>
>After Bxe4 c5 (a3,ect.), I tried Qe3, which also yields (if I don't have a
>serious bug) in a mate of the same length. Actually after Qe3, the tree looks
>more force to Yace. After giving the moves Qe3 Rf2 Bxg3 hxg3 h5 it takes a few
>seconds to find the mate, and perhaps about 1 minute to go back and see the mate
>score after c5.
>
>With this tree, I can show, that the root position is mate in 14 (or shorter):
>
>[Event "?"]
>[Site "?"]
>[Date "2002.12.30"]
>[Round "?"]
>[White "?"]
>[Black "?"]
>[Result "*"]
>[SetUp "1"]
>[FEN "b2r2kr/p1pqb1p1/1p5p/4p3/2P1N1P1/1P2Q3/P3P2P/4KRR1 b - -"]
>
>1... Bh4+ {5s} 2. Rg3 {3s} (2. Qg3 {12s} Qd1+ {3s} 3. Kf2
>{1s} Qd4+ {5s} 4. Kg2 {2s} Qxe4+ {2s} 5. Kh3 {6s} Bxg3
>{15s}) 2... Qd1+ {5s} 3. Kf2 {0s} Rf8+ {3s} 4. Qf3 {5s}
>(4. Nf6+ {20s} Rxf6+ {1s} 5. Qf3 {9s} Rxf3+ {1s} 6. exf3
>{4s} Qxf3+ {7s} (6... Bxg3+ {31s})) 4... Qd4+ {4s} 5. Kg2
>{5s} (5. Ke1 {13s} Rxf3 {5s} 6. exf3 {9s} (6. Rfxf3 {10s}
>Bxe4 {8s} 7. Kf1 {51s} (7. Rf5 {56s} Kh7 {16s}) 7... Qd1+
>{20s} 8. Kf2 {5s} Bxf3 {8s} 9. Kxf3 {4s} Kh7 {2s}) (6. Nf6+
>{1:11m} gxf6 {1s}) (6. Rf2 {1:46m} Qa1+ {18s}) 6... Bxe4
>{35s} 7. fxe4 {29s} (7. Rf2 {23s} Qa1+ {3s} 8. Ke2 {7s} Kh7
>{6s}) 7... Kh7 {3s}) 5... Bxe4 {4s} 6. Kh3 {9s} (6. c5
>{10s} Qe3 {2s} 7. Rf2 {11s} Bxg3 {3s} 8. hxg3 {1s} h5 {0s})
>(6. a3 {11s} Qe3 {2s} 7. Rf2 {4s} Bxg3 {3s} 8. hxg3 {1s} h5
>{0s}) (6. a4 {10s} Qe3 {2s} 7. Rf2 {4s} Bxg3 {1s} 8. hxg3
>{1s} h5 {0s}) (6. Kh1 {28s} Qe3 {6s}) (6. b4 {10s} Qe3 {2s}
>7. Rf2 {1s} Bxg3 {1s} 8. hxg3 {1s} h5 {0s}) (6. Rf2 {15s}
>Bxg3 {20s} 7. Kxg3 {7s} (7. hxg3 {12s} h5 {7s} 8. gxh5
>{14s} (8. g5 {11s} h4 {25s}) 8... Rxh5 {16s}) 7... Bxf3
>{24s} 8. exf3 {5s} h5 {0s}) (6. Qxe4 {16s} Qxe4+ {4s})
>(6. h3 {1:13m} Rxf3 {9s}) (6. g5 {10s} hxg5 {44s} 7. Rh3
>{7s} Rxf3 {12s}) 6... Bxf3 {19s} 7. exf3 {9s} Bxg3 {11s} *
>
>Cheers,
>Dieter
It seems that you need some hours to go backward in this tree to prove the mate
(the other possibilities that I can think about is that you improved yace
significantly here or that learning from going forward help fo going backward
faster).
At least when I try the the positions after 7...Bxg3 or the position after
6...Bxf3 ask for some minutes to see the mate score that you need.
Uri
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