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Subject: Re: mate threat extension/null move

Author: Zach Wegner

Date: 11:59:07 09/25/04

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On September 25, 2004 at 14:46:06, Peter Fendrich wrote:

>On September 25, 2004 at 13:51:39, Zach Wegner wrote:
>
>>>When you find a mate it first will get x > beta... Right?
>>>Then you will never reach the following statement.
>>>/Peter
>>
>>No, this is when the side to move gets mated, giving a score < -MATE + MAXPLY.
>>
>>Zach
>
>Right but I meant that return beta will not show -MATE+MAXPLY one ply up.
>This nulmove only code, however, and the answer is dependent of what's happening
>in the alpha/beta stuff later on...
>/Peter

Sorry, I misunderstood you. But the mate threat code is typically not (x < -MATE
+ MAXPLY) but (x == -MATE + ply + 2) so that first when the side to move is
mated it returns -MATE + ply (ply being 2 more than where the nullmove is
called) and then at ply + 1 it returns MATE - ply (this is a simple
change-return val instead of beta at a fail high)



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