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Subject: Re: Evaluation Approach

Author: Robert Hyatt

Date: 19:39:12 01/14/99

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On January 14, 1999 at 19:41:04, syed wrote:

>I thought the only place you could do an eval was at the terminal nodes. If you
>plan to do it somewhere in the middle wouldn't it interfere with your backed up
>scores?
>
>syed

not necessarily.  IE if you do an 8 ply search, you _could_ do your eval at
ply=5, and just pass that value down ply by ply to the ply=8 terminal position
where it could be backed up normally.  And it could be updated as it is passed
down if something significant happens to the position.

I believe that (at least at some point) Wchess was doing this...





>
>On January 14, 1999 at 17:49:15, KarinsDad wrote:
>
>>I have been considering the possibility of having two sets of evaluation
>>routines in my code. One set is a quick simplistic evalution and the other is a
>>slower, more detailed evaluation.
>>
>>The simplistic evaluation consists of any set of data which can quickly be
>>calculated such as material and safe squares. I was also going to have my pawn
>>structure score here as well since I am using one large hash table for it,
>>hence, since pawn structures are relatively stable and once calculated, they can
>>be re-used for multiple positions across the search tree.
>>
>>The detailed evaluation was going to consist of the simplistic evaluation, plus
>>modified piece values (based on where they are and what they are doing), square
>>control, king safety, etc.
>>
>>My questions are:
>>
>>1) Has anyone used an approach similar to this, and if so, is it successful? and
>>2) If I use this approach, where should I use each evaluation? I was thinking of
>>using the detailed evaluation only on the first few ply (maybe up to 4), on the
>>entire PV, and at the leaf nodes of non-quiescent paths (once they became
>>relatively quiescent again). I would then use the simplistic evaluation
>>everywhere else for speed. Does this seem reasonable, or am I missing something
>>here? Will having scores derived from two different evaluations result in a
>>skewing of the search?
>>
>>Thanks,
>>
>>KarinsDad



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