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Subject: Re: Schröder's new web page

Author: Uri Blass

Date: 23:20:53 12/29/02

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On December 28, 2002 at 19:03:33, Tony Werten wrote:

>On December 28, 2002 at 16:03:46, Uri Blass wrote:
>
>>On December 28, 2002 at 15:39:08, Tony Werten wrote:
>>
>>>On December 28, 2002 at 14:17:17, Alessandro Damiani wrote:
>>>
>>>>[snip]
>>>>
>>>>>
>>>>>the problem of most 'reductions' is the hard fact that you lose a full ply
>>>>>near the root.
>>>>
>>>>That's why reductions are not done in every node, but under certain conditions.
>>>>The quality then depends on those conditions, of course. Therefore, reductions
>>>>are not bad per se.
>>>
>>>This was about recursive reductions as FHR. What happens is at a ply you decide
>>>to reduce depth, but 2 ply later, the conditions are still met and you reduce
>>>another ply etc.
>>>
>>>I dumped them because they cost to much tactical strenght. Ed's nonrecursive way
>>>seem to give me a 5% node reduction. Not bad for 2 minutes work.
>>>
>>>Tony
>>
>>The question is still if it does not cost too much tactical strength.
>>
>>It is not clear if being 5% faster in 95% of the cases and seeing tactics one
>>ply later in 5% of the cases is a good idea.
>
>I had no case where I saw tactics one ply later. But then again, I didn't have
>the 15% speedup Ed mentioned either.
>
>Personally, I think I prefer the "safe" 5%.

I believe that more than 5% can be gained and the point is that if you get only
5% you need to check a lot of positions to verify that seeing tactics one ply
later is rare enough to justify pruning.

I believe that better conditions can be used for reduction and the gain should
be more than 15%.

I did not test it in movei because I already have different rules of pruning
based on evaluation.

Uri



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