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Subject: Re: One mate to solve.

Author: Heiner Marxen

Date: 03:44:37 07/18/01

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On July 17, 2001 at 22:09:08, leonid wrote:

>On July 17, 2001 at 19:27:49, Heiner Marxen wrote:
>
>>On July 17, 2001 at 08:33:49, leonid wrote:
>>
>>>Hello!
>>>
>>>This position you can try with every program. Its number of moves is only 89.
>>>
>>>[D]k1qnr3/1qq5/qn2Q3/qN1QqQ1K/qN2QqQ1/RbQQqQ2/1RrbQ3/2BB4 w - -
>>>
>>>Please indicate your result.
>>>
>>>Thanks,
>>>Leonid.
>>
>>Hi Leonid!
>
>Hi, Heiner!
>
>>This one is not as easy to solve for Chest, as usual.  After 2.6 hours on a
>>K7/600 with 350 MB hash it just found "no mate in 11".  The effective
>>branching factor has climbed from below 4 to above 10, so the next depth
>>most probably will need more than a day :-(  Hence I stop here.
>
>You are already there. Since you found mate in 11, it is mate in 12. My
>selective found mate in 12.

Fine!  From the increasing EBF I suspected already to be near the mate
(increased EBF does often occur in last depth with mate, and sometimes one
depth before it).

>Was able to reach only  10 moves deep by  brute force. It took already 11 hours
>and 17 min. I must for sure one day install my hash and see the difference. I
>hope in  few months from now to have my Linux computer  and start writing once
>again. For now I do almost nothing useful.

See estimated factor reached by hash in Chest below as "speed".

>My branching factor, as it happened very often, have the same tendency as your.
>It was 5, between 4 and 5 moves and ended by 9.2, between 9 and 10 moves.

The exact data to compare:

 depth   time    EBF[T]               EBF[N] speed
#  1      0.00s                 0kN           0.87          1-         0
#  2      0.00s                 0kN           1.00          1-         0
#  3      0.02s                 1kN [  8.43]  0.94         90-         0
#  4      0.09s [  4.50]        4kN [  5.51]  1.06        521-         0
#  5      0.37s [  4.11]       16kN [  3.82]  1.36       2000-         0
#  6      1.27s [  3.43]       55kN [  3.35]  1.62       6781-         0
#  7      4.84s [  3.81]      213kN [  3.90]  2.20      24475-         0
#  8     17.89s [  3.70]      896kN [  4.20]  3.05      84227-         0
#  9    111.61s [  6.24]     6190kN [  6.91]  3.23     519135-         0
# 10    870.30s [  7.80]    47882kN [  7.74]  3.46    4210571-      9399
# 11   9223.60s [ 10.60]   502283kN [ 10.49]  3.40   45603940-  36856039

The effect of the hash table is estimated to speed up by a factor of slightly
above 3.  That is not dramatic, but quite a difference.

Since the estimate sometimes is quite inaccurate, I have run it to depth 8
with hash completely disabled, and found:

#  3      0.01s                 1kN [  8.43]  1.00          0-         0
#  4      0.10s [ 10.00]        5kN [  6.27]  1.00          0-         0
#  5      0.53s [  5.30]       27kN [  5.50]  1.00          0-         0
#  6      2.74s [  5.17]      134kN [  5.01]  1.00          0-         0
#  7     14.30s [  5.22]      700kN [  5.22]  1.00          0-         0
#  8     68.14s [  4.77]     3405kN [  4.86]  1.00          0-         0

14.30 /  4.84 = 2.954  >  2.20
68.14 / 17.89 = 3.808  >  3.05

The real speed up appears to be even a bit larger than estimated.

Cheers,
Heiner



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