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Subject: Re: Verifiying mate depth

Author: Uri Blass

Date: 08:35:00 11/22/02

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On November 22, 2002 at 11:24:14, Dennis Breuker wrote:

>On November 22, 2002 at 10:30:34, Robert Hyatt wrote:
>
>>On November 22, 2002 at 07:21:13, Uri Blass wrote:
>>
>>>What do you search after finding a mate?
>>>Does genesis search for a shorter mate and in this case does it knows not to
>>>search when it get ply that means that no shorter mate can be found?
>>>
>>>Movei simply stop searching after finishing an iteration with mate score.
>>>
>>>Uri
>>
>>
>>I would suspect he does like most everyone else.  Search until you reach depth
>>2*N-1 where N is the mate depth as in mate in 9.  I need to search 17 plies to
>>verify that no shorter mate than mate in 9 exists...
>
>That's what I did as well. Until someone (was it Bas Hamstra, or
>maybe Walter Ravenek?) told me that 2*(N-1)-1 plies (so 15 in this
>case) is enough! If no mate is found within 15 plies then there is
>no mate in 8, so the mate in 9 must be shortest!
>
>Dennis

You assume no pruning and this assumption is usually wrong for chess programs.

Uri



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