Author: Daniel Shawul
Date: 00:57:50 04/21/04
Go up one level in this thread
On April 21, 2004 at 03:32:14, José Carlos wrote:
>On April 21, 2004 at 02:52:12, Daniel Shawul wrote:
>
>>On April 19, 2004 at 20:38:47, Mike Siler wrote:
>>
>>>My program tries a null move search if
>>>
>>>1. it's not the endgame
>>>2. it's not a PV node
>>>3. it didn't just make a null move
>>>4. it's not in check and wasn't in check on the previous ply
>>>5. the remaining depth isn't so small that the reduced depth would take it into
>>>the qsearch
>>>
>>>In general, only around 65% of the null move searches my program performs result
>>>in a cut-off. Is this normal or do other programs tend to do better (and how)?
>>>According to Ed Schröder's page, Rebel gets around 93-95%. I've tried the
>>
>>I am sure it does get that %. I just did a similar implementation like rebel's
>> evaluate internal nodes
>> if(score - our maximum hanging piece > beta)
>> don't do null move
>> This gives me usually >93% effectiveness! Thanks Ed.
>
> I don't know if Ed does only that, but in my experience it doesn't work. You
>must also take into account your own threats or you'll do unnecesary full
>searches. For example, eval is 0 and you have a hanging pawn, while beta is also
>0. The opponent has its queen and rook attaked by your pieces. A null move will
>save a lot of nodes there. The raise in % effectiveness is not enough to
>compensate for that, in my experience.
>
> José C.
sorry i made a typing error above
if(score - our maximum hanging < beta)
don't do null move
Or
if(score - our maximum hanging + opponent's maximum hanging < beta)
don't do null move
The second one may solve the problem you mentioned.
>
>
>>>recommendations listed there but they didn't help much.
>>>
>>>Michael
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