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Subject: Re: One easy mate to solve.

Author: Heiner Marxen

Date: 04:18:33 07/22/01

Go up one level in this thread


On July 21, 2001 at 12:35:35, Gian-Carlo Pascutto wrote:

>On July 21, 2001 at 04:39:07, leonid wrote:
>
>>Hi!
>>
>>Probably next position will be easy for every program.
>>
>>[D]knqb2Rq/qbq2Qq1/nq2Nr2/q2QQQ2/2NQQ3/1QrQ4/Rq4BB/q5QK w - -
>>
>>Please indicate your result.
>>
>>Thanks,
>>Leonid.
>
>2.5 seconds
>
>Sjeng: prove
>
>Max time to search (s): 200000
>
>P: 0 D: 100000000 N: 186965 S: 186964 Mem: 7.85M Iters: 2132 MaxDepth: 29
>Time : 2.500000
>This position is WON.
>PV: e6c7 a6c7 d5b7 b6b7 d4a7 a5a7 e4b7 c8b7 g2b7
>
>
>--
>GCP

For Chest to prove the shortest mate this is much harder:  after 13.4 hours
Chest says "No solution in 11 moves."  (K7/600 with 350 MB hash)
The EBF is not bad, but also not good enough: starting with depth=8 black
has used up the easy checks, and the EBF doubles:

 depth  time     EBF[T]              EBF[N]  hash-speed
#  1      0.00s                 0kN           0.87          1-         0
#  2      0.00s                 0kN           1.00          1-         0
#  3      0.01s                 1kN [  8.23]  0.92         99-         0
#  4      0.10s [ 10.00]        4kN [  5.22]  1.02        595-         0
#  5      0.47s [  4.70]       19kN [  4.21]  1.23       2521-         0
#  6      2.02s [  4.30]       85kN [  4.56]  1.46      10289-         0
#  7      8.82s [  4.37]      417kN [  4.91]  1.71      42237-         0
#  8     69.52s [  7.88]     3568kN [  8.56]  1.84     335095-         0
#  9    595.42s [  8.56]    31094kN [  8.72]  2.13    2951616-       802
# 10   4980.94s [  8.37]   260558kN [  8.38]  2.45   25194399-  16446522
# 11  48350.46s [  9.71]  2531658kN [  9.72]  2.62  242162073- 233414172

Depth=12 is estimated to need more than 5 days  :-(  So Chest quits here.
Apparently, Chest needs a fast mate search mode to not frustrate its author
so often  :-)

Cheers,
Heiner



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