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Subject: Re: evaluation tuning tricks

Author: Uri Blass

Date: 08:08:24 03/17/04

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On March 17, 2004 at 11:04:20, Fabien Letouzey wrote:

>On March 17, 2004 at 10:27:34, Tom Likens wrote:
>
>>On March 17, 2004 at 09:52:27, Tord Romstad wrote:
>>
>>>On March 17, 2004 at 04:58:06, Peter Alloysius wrote:
>>>
>>>>what are tricks for evaluation tuning so that it could
>>>>search less nodes?
>>>
>>>An easy way to reduce your tree size enormously is to evaluate all
>>>positions to the value 0.  You will get beta cutoffs at the first move
>>>everywhere in the tree, therefore the tree will be extremely small.  Your
>>>move ordering will always be perfect, and the simple evaluation function
>>>will certainly boost your nodes/second count.  :-)
>>>
>>>Seriously, I don't think tuning the evaluation is the right way to go
>>>in order to reduce the tree size.  You should rather concentrate on
>>>making the evaluation function as accurate as possible, and look for
>>>improvements in your search and move ordering when trying to reduce the
>>>size of your tree.
>>>
>>>Tord
>>
>>Ah ha!!  I knew there was a final *secret* you weren't sharing Tord, but now the
>>cat is out of
>>the bag.  After reading this I've replaced my evaluation function completely
>>with...
>>
>>return 0;
>>
>>and it has *never* been faster.
>>
>>--tom
>>
>
>
>That's only the beginning.
>
>Now that the first move always gives the best score, you don't need to search
>the other ones anymore ...
>
>There are many secrets you did not know about apparently!
>
>Fabien.

There is only one problem

evaluating mate position as 0.00 is not a very good idea for results and if your
0.00 is for every position except mates then you cannot be sure that the first
move always give the best score.

Uri



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