Author: José Carlos
Date: 08:01:46 03/31/02
Go up one level in this thread
On March 31, 2002 at 08:40:26, Klaus Friedel wrote:
>On March 31, 2002 at 07:22:25, Uri Blass wrote:
>
>>On March 31, 2002 at 07:10:41, José Carlos wrote:
>>
>>>On March 31, 2002 at 06:17:15, Klaus Friedel wrote:
>>>
>>>>Has anybody ever tried something like that in his null move code :
>>>>
>>>>
>>>> int nullDepth = depth - (NULL_REDUCE + 1)*DEPTH_BASE;
>>>>
>>>> if(tryNull){
>>>> executeNullMove();
>>>> beta -= NULL_BONUS;
>>>> value = - search(nullDepth, -beta, -beta+1, ply + 1);
>>>> undoNullMove();
>>>> if(value >= beta){
>>>> beta += NULL_BONUS;
>>>> ttStore();
>>>> return beta;
>>>> }
>>>> beta += NULL_BONUS;
>>>> }
>>>>
>>>>
>>>>Bigger values of NULL_BONUS increase the count of nodes prunded (but you migth
>>>>oversee some tactics). Values of about 30cp made my engine ply slightly better
>>>>than the default null-move (NULL_BONUS = 0).
>>>>
>>>>
>>>>Klaus
>>>
>>> A couple of thoughts:
>>> - You can be a bit faster declaring nullDepth inside the "if" and doing "beta
>>>+= NULL_BONUS;" just once, before "if(value >= beta){"
>>
>>The code is going ot be slightly shorter but I do not see
>>why is it going to be faster and it seems to me the same speed.
>>
>>You suggest to replace
>>
>>if(value >= beta)
>>{
>> beta += NULL_BONUS;
>> ttStore();
>> return beta;
>>}
>> beta += NULL_BONUS;
>>
>>by the following code:
>>
>>beta+=NULL_BONUS;
>>if(value >= beta)
>>{
>> ttStore();
>> return beta;
>>}
>>
>>In both cases beta+=NULL_BONUS is done exactly once in every case
>>so I do not see a reason that the shorter code
>>is going to be the faster code.
>>
>>Uri
>
>The code I posted is not complete. As posted here anyone would move some
>statements. But thats not the point, as it doesn't affect functionality.
>
>The question is: Does the lower branching factor gained by moving the
>null-window weight out the danger of pruning away important lines.
>
>Your "improvement" is wrong. If you move the line "beta+=NULL_BONUS" you have to
>adjust the if-expression:
>
>beta += NULL_BONUS;
>if(value >= beta - NULL_BONUS){
> ttStore();
> return beta;
>}
Sorry. Of course you're right.
José C.
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