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Subject: Re: Side effects of lazy eval?

Author: Vincent Diepeveen

Date: 09:02:42 09/28/00

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On September 28, 2000 at 11:41:50, Dieter Buerssner wrote:

>On September 28, 2000 at 05:00:59, Bas Hamstra wrote:
>
>>On September 27, 2000 at 16:16:21, Peter McKenzie wrote:
>>
>>>On September 27, 2000 at 07:47:18, Bas Hamstra wrote:
>>>
>>>>Supposing no "lazy-errors" at all were made, does anyone know if there are
>>>>serious side-effects to lazy eval?
>>>
>>>You can't get the full benefits of fail-soft using lazy eval.
>>
>>I agree. This is the only factor I can think off too, you lose some bound info.
>>
>>Yet, I ran a couple of WAC tests at very short time controls, with and without
>>LE. And kept track of the average depth that was reached. In that quick test
>>NPS went up, but the average depth stayed the same!
>>
>>So it seems what you win in speed, you lose in bound info, net result zero? At
>>least in this case. I will rerun it more accurately, at longer tc.
>
>You might want to give the following idea a try. I think this could be called a
>fail soft version of lazy eval:

I heart someone mention this trick before a couple of years ago,
but when i measured the largest eval score i had so far during the
search the trick looked a bit silly

>    es = s + largest_evalscore[side];

So that's roughly (can be a bit more or less):

  es = s + 20 pawns

 ..do i need to continue?

>    if (es < alpha)
>      return es; /* fail hard: return alpha */
>    es = s - largest_evalscore[xside];
>    if (es > beta)
>      return es; /* fail soft: return beta */
>
>This should store better bounds in the hash tables.

Way worse bounds.

>-- Dieter



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