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Subject: Re: Two mate positions to solve.

Author: leonid

Date: 22:01:52 09/03/00

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On September 03, 2000 at 19:42:33, leonid wrote:

>On September 03, 2000 at 15:50:44, Uri Blass wrote:
>
>>On September 02, 2000 at 17:08:20, leonid wrote:
>>
>>>Hello!
>>>
>>>Please solve these two positions and say minimum number of moves that lead to
>>>it.
>>>
>>> 1r2k2r/1b3pbp/1NPqN1n1/1P1Q4/1P2P3/P3B3/5PP1/R3KB1R White to go.
>>
>>Qxd6 mate in 6
>>>
>>> 6KQ/3B2Q1/QQQQQQQ1/5Nbn/qqqqq1q1/5qqk/8/8 White to go.
>>
>>Qgxh5+ mate in 8.
>>>
>>>It will be good if you will indicate all main parameters of your trial. At
>>>least, I see them this way:
>>>
>>>Name of your program. Hash table size.
>>
>>Junior5.9(64 mbytes)
>>>In what way (if you know) position was solved. Selective search or brute force
>>>search.
>>
>>Selective search(Junior like other top program does not do brute force search.
>>>Time for each way of search.
>>
>>7 seconds for the first position.
>>55 seconds for the second position.
>>>CPU and its speed.
>>
>>P200MMX
>>
>>
>>Uri
>
>Excellent! Now I know even lesser number of moves that lead to mate in second
>position. The first I knew that it was in 6 moves since it was so close. Will
>see later if 8 moves for the last position are the short one. But even 8 moves
>verification for so heavy position could take some time.
>
>Leonid.

Went to verify if your number is exact as minimum. Exact!

AMD 400Mhz. Mate solver in llchess. No hash tables.

Tried by brute force up to 7 moves to see if much shorter mate not existe.

4 moves - 1 sec.                 No mate.
5 moves - 19 sec.                No mate.
6 moves - 8 min 1 sec.           No mate
7 moves - 3 hours 40 min 39 sec. No mate.

Did not tried to solve this position by brute force in 8 moves. Knew after time
that 7 moves took that it could be time expensive. Went to see if quickest
selective solver will solve this position with new parameter. Gave to selective
search permition to search one node more in each ply. Mate was immidiatelly
found in 8 moves. Time 0.2 sec. Move: queen goes d6-g3.

Leonid.



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