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Subject: Re: One mate to solve.

Author: leonid

Date: 11:34:41 09/30/01

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On September 30, 2001 at 13:51:05, Paul wrote:

>On September 30, 2001 at 13:21:49, leonid wrote:
>
>>On September 30, 2001 at 12:26:48, Paul wrote:
>>
>>>On September 30, 2001 at 11:06:55, leonid wrote:
>>>
>>>>Hello!
>>>>
>>>>Since my computer had no Web connection for more that one week, I accumulated
>>>>many new positions. Will place here, at least, one of them.
>>>>
>>>>[D]qbbqnqqq/3Pq3/3Pq3/3Qq3/2PQBn2/1K1NB1k1/Q2NR2q/3QR3 w - -
>>>>
>>>>It could be that somebody will recognize this position as Chinese character
>>>>"NO". Its origin is curious. Invented, as many other characters, to contain some
>>>>visual or logical connotation, it contain one. Picture, or logic, help in
>>>>remebering each character. In this, horizontal line stays for higher limit of
>>>>the sky, while below it is a bird that try to reach it. Since bird can never fly
>>>>up to upper line on the sky this character indicate negation, "NO".
>>>>
>>>>Please indicate your result.
>>>>
>>>>Leonid.
>>>
>>>Hi Leonid,
>>
>>Hi, Paul!
>>>
>>>I'll give it another try ... the more data I get about my bug the better.
>>>Pretz found a mate in 9 here:
>>
>>Your Pretz is perfect! This is mate in 9. I solved this position by brute force
>>and this is why I am sure.
>>
>>
>>>00:17 WM9 07 Bxf4+ Qfxf4 Rg1+ Qxg1 Q1xg1+ Kh4 Rh2+ Qh3 Rxh3+ Kxh3 Nxf4+ Qxf4
>>>Bg2+ Qxg2 Qgxg2+ Kh4 Qxf4#
>>>
>>>and for black it says mate in 8. Hope you'll give us some mate in 12 or 13's in
>>>the near future, is better for my testing.
>>
>>This is nice finding. I looked into position but had impression that mate for
>>black is not there. I was wrong. Will ask later mate for black side.
>
>That's a surprise, because it seems very easy (1 second):

Even if it look like easy, I thought that after d8-b6, white queen will take
black queen without any bad consequences, with the move d5-b6. What I was not
able to see is that white will be mated instantly if they will move this way.
Program see those positions much better that human can.

I went to ask mate for blacks and found that shortest mate existe in 8. So, your
program found shortest mate and is very efficent and bright.

My time for selective was 2 seconds. Search by brute force was very easy, since
branching factor was around 5. Brute force time was 1 min for 8 moves.
Verification for 7 moves took 53 seconds to say no. Celeron 600.

Cheers,
Leonid.

>00:01 BM8 06 Qb6+ Nb4 Qxb4+ Kxb4 Q7xd6+ Qxd6 Q6xd6+ Kc3 Qb4+ Kc2 Qxa2+ Kc1 Qab2+
>Qxb2 Qexb2#
>
>Groetjes,
>Paul



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