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Subject: Re: Fritz 7.0.0.6 has futility pruning on as default.

Author: Bas Hamstra

Date: 06:52:35 01/27/02

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On January 27, 2002 at 06:43:31, David Rasmussen wrote:

>On January 27, 2002 at 06:20:59, Bas Hamstra wrote:
>
>>[D]r2r1bk1/ppqb1ppp/2p1p3/6P1/2PPN3/PB3Q2/1P3P1P/1K1RR3 w - - Nf6!!
>>
>>Tao solves this in a couple of minutes (I believe 4 minutes to resolve the fail
>>high). But with futility pruning turned on it doesn't. I am curious how it
>
>What fail high? I thought that Tao didn't use an aspiration window at the root.
>So how can it have a fail high to resolve? Or do you mean elsewhere in the tree,
>and then, how do you know that what is taking time is resolving a fail high?
>
>/David

That's when I call it when a new move is found after many iterations. Till 12
ply it likes g6, and then suddenly Nf6 is discovered. This fails high on my
<alpha, alpha+1> PVS window at the root. A research with bigger window takes a
lot of time (resolve FH) in this case.

How do I know? Well if at ply 12 the search freezes for many minutes and the new
move Nf6 comes out, that's what happened.

Best regards,
Bas.





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