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Subject: Re: One mate to solve.

Author: leonid

Date: 20:01:01 03/23/02

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On March 23, 2002 at 17:42:08, Heiner Marxen wrote:

>On March 23, 2002 at 08:59:03, leonid wrote:
>
>>[D]q1q1kq1q/3bb3/Q1RqqR1Q/1NBrrBN1/3q4/Qn4nQ/1P2P1P1/q1Q1KQ1q w - -
>>
>>Please indicate your result.
>>
>>Thanks,
>>Leonid.
>
>In 16.5 minutes on my K7/600 (350 MB hash just half full) Chest finds
>a mate in 11 with 2 key moves:

Good! I know only that this is mate in 11 but do not know that it contain two
solutions.

>PV: Bg6+ Kd8 Bb6+ Qxb6 Nxe6+ Rxe6 Rxf8+ Qxf8 Rxc8+ Qxc8 Qxb6+ Qcc7 Qa8+ Bc8
>Qxf8+ Bxf8 Qxc8+ Kxc8 Qxe6+ Qd7 Qxc7#
>PV: Rxf8+ Qxf8 Bg6+ Kd8 Bb6+ Qxb6 Nxe6+ Rxe6 Rxc8+ Qxc8 Qxb6+ Qcc7 Qa8+ Bc8
>Qxf8+ Bxf8 Qxc8+ Kxc8 Qxe6+ Qd7 Qxc7#
>
>The EBF was quite small due to good direct mate threats of black, like Qxf1#,
>Qxc1# and Rxe2#:
>
>#  4      0.08s [  8.00]        7kN [  7.63]  1.16        229-         0
>#  5      0.46s [  5.75]       36kN [  5.06]  1.60       1017-         0
>#  6      1.98s [  4.30]      150kN [  4.20]  2.30       5540-         0
>#  7      6.97s [  3.52]      512kN [  3.43]  3.58      21409-         0
>#  8     25.49s [  3.66]     1805kN [  3.52]  5.05      88508-         0
>#  9     94.49s [  3.71]     6429kN [  3.56]  6.37     372339-         0
># 10    292.18s [  3.09]    18945kN [  2.95]  8.12    1307115-         4
># 11    992.84s [  3.40]    60719kN [  3.21]  8.88    4870834-     26187
>
>I suspect your selective search also found the mate in 11.

No. Mine found mate in 11 only by selective and it was pretty slow. Selective in
11 took already more that 4 minutes.

It could be that we have almost identical branching when search goes without
hash. Mine searched went by brute force only 10 moves deep.

It was:

Moves         Time         Branching factor          NPS

4             0.439 sec                              108k
                           6.12
5             2.69 sec                               91k
                           6.04
6             16.26 sec                              77k
                           5.38
7             1 min 27                               69k
                           4.89
8             7 min 8 sec                            66k
                           4.89
9             34 min 59 sec                          62k
                           3.91
10            2 h 16 m 27 sec                        59k

It is interesting that your program had identical tendency with its branching
factor decline as mine.

I still wait that somebody will come with some brute force solutions as your
program. For more that one year, I never could see any other program beyond
your. Very strange! It could that it is not that simple, as it look like.

Cheers,
Leonid.

>Cheers,
>Heiner



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