Author: Andrew Williams
Date: 14:38:40 03/13/04
Go up one level in this thread
On March 13, 2004 at 17:32:49, Uri Blass wrote:
>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.
>
Are you suggesting that crafty checks for a hash cutoff *after* searching the
current position? That seems a bit unlikely. Perhaps you have misunderstood
Bob's code?
Andrew
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