Author: Uri Blass
Date: 14:32:49 03/13/04
Go up one level in this thread
On March 13, 2004 at 17:12:49, Andrew Williams wrote:
>On March 13, 2004 at 16:27:22, Uri Blass wrote:
>
>>On March 13, 2004 at 16:14:39, Anthony Cozzie wrote:
>>
>>>On March 13, 2004 at 15:51:12, Uri Blass wrote:
>>>
>>>>I redesign my alphabeta and I think to start my alphabeta by trying null move
>>>>because checking for repetition or for hash cut off can be done at the end of
>>>>alpha beta.
>>>>
>>>>When I look at Crafty's code I see that Crafty starts not with null move but
>>>>with checking for repetition and hash.
>>>>
>>>>My question is if there is a soecial reason that I do not understand that Crafty
>>>>does it.
>>>>It seems to me a waste of time to call alphabeta with all the parameters when it
>>>>can be avoided.
>>>>
>>>>Uri
>>>
>>>Which costs more: checking for a repetition, or searching a subtree?
>>>
>>>anthony
>>
>>I do not understand the reason for this question.
>>
>>I need to check for repetition in any case but I think that it is better to do
>>it not in the beginning of alphabeta but before you call alphabeta.
>>
>>
>>
>>Crafty has
>>search(a lot of parameters)
>>{
>>1)check for repetition or hash cutoff
>>2)make null move to see if you can prune based on null move
>>3)for all moves
>>a)make move
>>b)calculate extensions
>>c)search(a lot of parameters)
>>
>>I think that it should be
>>
>>1)make null move
>>2)for all moves
>>a)make move
>>b)calculate extensions
>>c)check if you can cut based on repetition or hash cut off
>>d)call search(a lot of parameters)
>>
>>Am I missing something?
>>
>>Uri
>
>After you make a null move, you *search* (REMAININGDEPTH-REDUCTIONFACTOR).
>Although this is obviously less than a normal search (which would be to
>REMAININGDEPTH), it is still a search. Normally a check for a hash cutoff is
>just a probe into the hash table. A check for repetition just means checking the
>last few positions to see if the hash signature is the same as the current
>position.
>
>Generally, you'd do the null move search *last*, because it will take more time
>than the other two.
I think that you do not understand my idea
I suggest to do exactly the same things in the same order but to check for
repetition or hash cut off before calling search and not after calling search.
Uri
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