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Subject: Re: Easy mate

Author: Dieter Buerssner

Date: 15:20:56 09/13/03

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On September 13, 2003 at 14:31:55, Rafael Andrist wrote:

>On September 13, 2003 at 14:08:37, John Merlino wrote:
>
>>On September 13, 2003 at 10:23:41, Frank Phillips wrote:
>>
>>>8/4k3/8/8/4Kp1p/5N1N/8/8 w - -

>>Kxf4 is a forced mate in 90 moves and it will NOT be caught by the 50-move rule.
>
>No, after Kxf4 it is a draw. You need 51 moves to the next forced capture/pawn
>push with best defence.

My TB-generator does confirm this more or less. It minimaxes the distance to the
next pawn push or capture, and the result is: lost in 52 (which will be set to
draw, when my testing phase is finished). Note, that this does not contradict
your finding. Probably, black can go for a shorter mate (in Nalimov sense -
minimaxing for shortest mate), and thereby can delay the capture/pawn push for 1
more move.

I guess, that in similar positions also the other way around my be possible:
white goes for a longer mate, but can force a pawn-push/capture faster by this.

Of course, in this specific endgame, capture is normally not correct.

BTW. Generating the knnkp database took 15 minutes and used less than 40 MB of
RAM. When I wrote up a bit more code, I can show the line.

Regards,
Dieter




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