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Subject: Re: KBN vrs K on 10x10 board -- Mate in 47

Author: Uri Blass

Date: 16:17:52 09/20/00

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On September 20, 2000 at 18:19:57, Vincent Diepeveen wrote:

>On September 18, 2000 at 23:51:59, Uri Blass wrote:
>
>>On September 18, 2000 at 20:43:56, James B. Shearer wrote:
>>
>>>On September 18, 2000 at 17:28:56, Bruce Moreland wrote:
>>>
>>>                  <snip>
>>>
>>>>The above might have bugs.  If not, it's the worst case with white to move, mate
>>>>in 47.  This looks like a harder case than the standard 8 x 8 board, since black
>>>>can start out in a corner, constrain white for a bit, then evade to the center,
>>>>since, I presume, the knight is too slow to catch black.  In the 8 x 8 version,
>>>>black starts out in the center in the worst case.
>>>>
>>>>KR vs K is a mate in 21, and KQ vs K is a mate in 12.
>>>>
>>>>I can't do a 9 x 9 board as easily as a 10 x 10 board, but I think it may be
>>>>possible that you could have a "wrong" bishop in KNB vs K with that sized board,
>>>>so it could be a draw in some cases.
>>>>
>>>>bruce
>>>
>>>     This is interesting.  How about Q vrs R?
>>>     47 moves isn't as many as I would have guessed and makes me suspect you can
>>>mate with B and N on any board with a corner of the right color.  12x12 would be
>>>the next case to try.
>>>                             James B. Shearer
>>
>>My guess is that if the board is big enough you cannot mate because you cannot
>>lead the king from one corner to another one.
>>
>>I do not say that 12 is big enough.
>>
>>Uri
>
>You can always close in the king of course by making the corner smaller.
>
>the theory is real simple. just make the diagonal smaller and smaller.
>you have 2 pieces and a KING to close in the king into a smaller and
>smaller diagonal. It'll be hell of a work to mate someone on a 100x100,
>but he. Just bet for money that i can't do it...

You may be right and the numbers of Bruce in 12*12 board suggest that you are
right.

I did not learn seriously the way to mate KBN vs K and I only know that there is
a stage when the king can escape from the last rank by Kd8-e8-f7 only to get
later to it again.

Uri



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