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Subject: Re: Tree search programs

Author: Uri Blass

Date: 06:54:56 05/25/03

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On May 25, 2003 at 09:39:48, JW de Kort wrote:

>On May 25, 2003 at 08:48:31, Uri Blass wrote:
>
>>On May 25, 2003 at 07:53:59, JW de Kort wrote:
>>
>>>Hi friends,
>>>
>>>My chess engine currently has two search related problems.
>>>
>>>1) Sometime a e.g. 8 ply search only returns a pv a say 4 or 5 or sometimes even
>>>only one move. Can this be a result of using the hashtable?
>>>
>>>2) The engine searches until a certain amount of time is spend.
>>
>>This is a mistake because if there is a fail low it is better to use more time
>>aqnd there are cases when it is better not to use time for your move(if there is
>>a single move).
>>
>> If the search
>>>notices that the time has ran out, the search is stopped an beta is returned.
>>
>>Why do you return beta?
>>
>> I
>>>think this is the correct thing to do.
>>
>>No
>>It is not.
>>Your engine should play the best move that it found and not a move that it
>>considers.
>>
>>I see no reason to return beta when you have no idea about the score.
>>
>>Uri
>
>Thanks Uri for your reply. I will explain.
>Suppose the engine has reached a debt of 5 ply and then time has run out. The
>search must be terminated. Alpha bet is a recursive algorithm so something has
>to be returned because the iteration has to stop. I use beta because to signal
>that the move is less in value than all the other moves searched so far. I'am
>not sure that this is the correct procedure, though.
>
>How do you go about?
>
>Thanks again

I do not understand what you are talking about.
I remember the best move in the pv and if the pv is not updated the move in the
pv is played.

Uri



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