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Subject: Re: Heavy mate position but easy to solve.

Author: leonid

Date: 22:55:42 10/20/03

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On October 20, 2003 at 21:29:28, Steven J. Brann wrote:

>On October 20, 2003 at 09:09:19, leonid wrote:
>
>>Hi,
>>
>>The next position is very easy to solve but it contain pretty heavy pieces. It
>>cold be good for checking program for robustness.
>>
>>[D] 2r1N2B/PP1RqP1Q/K2nnq1R/Npk3q1/3q1qQr/2qbbQ2/1P1Q3q/1q1B1Q2 w - -
>>
>>Please indicate Your result.
>>
>>Leonid.
>
>CM9K on a 3.0G P4 (default personlity with SS=12 and 128MB hash) finds a Mate in
>10 in one second and doesn't seem to be able to improve on it.
>
>Time	Depth	Score	Positions	Moves
>0:01	1/3	Mate10	171669		1.Qxc3+ Qxc3 2.bxc8=Q+ Nxc8 3.Qc6+
>					Kb4 4.Qxc3+ Qxc3 5.Bxc3+ Kc5 6.Nb3+
>					Kc6 7.Rxe6+ Qed6 8.Rexd6+ Nxd6
>					9.Rxd6+ Qxd6 10.a8=Q#
>0:04	1/4	Mate10	592197		1.Qxc3+ Qxc3 2.bxc8=Q+ Nxc8 3.Qc6+
>					Kb4 4.Qxc3+ Qxc3 5.Bxc3+ Kc5 6.Nb3+
>					Kc6 7.Rxe6+ Qed6 8.Rexd6+ Nxd6
>					9.Rxd6+ Qxd6 10.a8=Q#
>0:17	1/5	Mate10	2530379		1.Qxc3+ Qxc3 2.bxc8=Q+ Nxc8 3.Qc6+
>					Kb4 4.Qxc3+ Qxc3 5.Bxc3+ Kc5 6.Nb3+
>					Kc6 7.Rxe6+ Qed6 8.Rexd6+ Nxd6
>					9.Rxd6+ Qxd6 10.a8=Q#
>1:16	1/6	Mate10	11423726	1.Qxc3+ Qxc3 2.bxc8=Q+ Nxc8 3.Qc6+
>					Kb4 4.Qxc3+ Qxc3 5.Bxc3+ Kc5 6.Nb3+
>					Kc6 7.Rxe6+ Qed6 8.Rexd6+ Nxd6
>					9.Rxd6+ Qxd6 10.a8=Q#
>4:27	1/7	Mate10	40341857	1.Qxc3+ Qxc3 2.bxc8=Q+ Nxc8 3.Qc6+
>					Kb4 4.Qxc3+ Qxc3 5.Bxc3+ Kc5 6.Nb3+
>					Kc6 7.Rxe6+ Qed6 8.Rexd6+ Nxd6
>					9.Rxd6+ Qxd6 10.a8=Q#


It could be mate in 10. I know for sure that my program found mate by selective
in 10 moves and it went by brute force stopping before 9. So, only 9 moves was
not verified. I not verified 9 moves, since suddenly between 7 and 8 move
branching factor doubled and arrive to 11. With time for 8 moves 47 minutes, it
looked to be long to search for 9. Obviously, with quick computer and program
that use hash this verification is very accessible.

Like I expected solution of this position by selective was easy. Your result was
practically indentical to mine . Mine found mate in 10, in 2.7 seconds but went
on slower computer and without hash. Number of position/second for Your search
was very close to mine. Mine had average 210000 position/second for brute force
search when searching 8 moves deep.

Leonid.

>Steve



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