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Subject: Re: Live chat with Feng-Hsiung Hsu (of Deep Blue fame) on ICC

Author: Jeremiah Penery

Date: 08:32:11 10/11/02

Go up one level in this thread


On October 11, 2002 at 11:15:14, Vincent Diepeveen wrote:

>On October 11, 2002 at 11:11:01, Jeremiah Penery wrote:
>
>>On October 11, 2002 at 10:46:16, Gian-Carlo Pascutto wrote:
>>
>>>On October 11, 2002 at 10:38:12, Jeremiah Penery wrote:
>>>
>>>>On October 11, 2002 at 08:09:59, Vincent Diepeveen wrote:
>>>>
>>>>>you skip one important point. Because of a simplistic evaluation
>>>>>it was able to get 12.2 ply. If you use a more complex evaluation
>>>>>then you do fullwidth not get 12.2 ply at all, but more like 10.5 ply.
>>>>
>>>>It did evaluation in hardware.  The complexity of the function has NOTHING to do
>>>>with the speed of computing it.  This is obviously something you don't
>>>>understand, or you wouldn't be writing crap like the above, or the below.
>>>
>>>You missed Vincents point. His point was that a more complicated
>>>evaluation (with bigger positional scores) will slow down the search
>>>compared to (for example) a piece-square evaluation, because it causes
>>>more instability.
>>
>>Having a more complicated evaluation does not require having bigger positional
>>scores, but I agree that in the general case that is what happens.  However,
>>search instability depends on the correctness of your evaluation function and
>>your move ordering - the variability of the evaluation function is secondary.
>>If your evaluation is very complex, but also extremely accurate, it will be far
>>more stable than a simpler but less accurate evaluation will yield.
>
>If you always return 0 as score, then any move will give a cutoff.

I wouldn't call that an evaluation function.

>If you are material based, just material, then capturing a piece will
>give usually a cutoff.

For the overly simple case(s) (only material or similar), you're correct.  I was
using 'simple' evaluation to mean something like piece/square tables plus a few
basic positional things.  Material only is uninteresting.

>If you have a complex evaluation, then you do not know in advance whether
>trying a capture is going to give a cutoff. Obviously it's harder to order
>moves too. If you knew ahead which move would going to give a cutoff for you,
>why the hell would you do a search anyway?

Why is it harder to order moves when you have a more complex evaluation?  It
would seem to depend more on the accuracy of the evaluation, rather than the
complexity.



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