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Subject: Re: what do you update during null move

Author: Uri Blass

Date: 15:17:59 09/03/03

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On September 03, 2003 at 17:38:02, Rafael Andrist wrote:

>On September 03, 2003 at 16:49:47, Uri Blass wrote:
>
>>>>2)The history ply and all the arrays in the struct that are dependent on it.
>>>
>>>That depends on how you organised your data structure. I use this history
>>>information only for repetition checks and for updating the PV. For me it does
>>>not matter if I increase the history ply or not.
>>
>>If you use it for repeptition detection then it should matter.
>
>Compare these two possibilities:
>
>1) Array with the root of the Nullmove subtree
>
><...>
><last position before Nullmove>
><position after Nullmove (only stm change and ep reset)>
><first position after a real move in the Nullmove subtree>
><...>
>
>2) Array without the root of the Nullmove subtree
>
><...>
><last position before Nullmove>
><first position after a real move in the Nullmove subtree>
><...>
>
>If you use no. 2, increasing the history plycount introduces an error, if you
>use no. 1, you of course have to increase the history plycount.

I use 2 and do not increase the history count but I think that it is an error
and I should use 1.

I have 2 variables ply and hply
hply is the ply from the beginning of the game.
ply is the ply from the beginning of the search(ply=0 in the root position of
the search)

The problem is that my repetition detection is based on the full game and if
I go back 2 plies every time, then the side to move is changed when there is
null move that is not considered in the middle.

Uri



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