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Subject: Re: q search nps question

Author: Robert Hyatt

Date: 09:25:46 01/07/00

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On January 07, 2000 at 03:56:37, Landon Rabern wrote:

>I jsut added a q-search to my program and it dropped from 180,000 nps to
>90,000 nps.  I count leaf nodes when counting my nodes, so I though it might be
>that the q-search has no leaf nodes, so I was not getting these free no-work
>nodes.  This wasn't it though, because I tried incrementing the nope counter
>where a leaf node would have been had it been a regular search, but this only
>improved it slightly.  I am pretty sure that it is actually running a lot
>slower.  Is it supposed to do this?
>
>Thanks,
>
>Landon W. Rabern


The issue is how do you generate captures.  If you generate all moves, and
then extract the captures for the q-search, your nps must drop, because of
all the extra work you do but never take advantage of.  The q-search is
more selective, meaning that for each node you reach in the q-search, you do
the usual amount of work in the alpha/beta search, and so forth, but you only
look at a couple of branches.  That drops the NPS significantly.



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