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Subject: Re: what do you update during null move

Author: Rafael Andrist

Date: 14:38:02 09/03/03

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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.


>>Do you have two different hashkeys, one for the table and one for repetition
>>checking?
>
>No
>
>The hash key is the same hash key but I remember it as a global varaible and
>also in the array after making normal moves(I should remember it in the array
>also after making null moves but I forgot about it when I implemented hash
>tables(If I remember correctly hash was implemented after null move).

IMO you should update the hashkeys in both places and keep them synchronous.

regards
Rafael B. Andrist



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