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Subject: Re: Tree search programs

Author: JW de Kort

Date: 06:41:48 05/25/03

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On May 25, 2003 at 08:03:46, Tom Kerrigan 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?
>
>The obvious possibility is that there was contention for the hash table entry
>that would have contained the rest of your PV. There may be additional
>explanations too.
>
>>2) The engine searches until a certain amount of time is spend. If the search
>>notices that the time has ran out, the search is stopped an beta is returned. I
>>think this is the correct thing to do. BUT the following happens: sometimes a 8
>>or 9 ply search is done and a correct move (at least a correct move in the eye
>>of my engine) is found but then suddenly a completely different move is
>>selected, most of the cases this is a blunder and often the evaluation drops
>>with about the score of a bishop because a bishop is lost. It is nice to have
>>written a enging playing like a human, but i would rather remove this problem.
>
>When time runs out, my program just stops searching and doesn't try to do
>anything clever that might be wrong. After every call to search, I check
>stop_search, and if it's TRUE, I return 0...
>
>-Tom

Thanks Tom,

i do not quit get what you mean. Suppose the engine has reached a depth of 4 ply
and time runs out. Then some value has to returned to depth 3. I use beta for
this. How do you solve this problem?

thanks
Jan WIllem




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