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Subject: Re: Funny position !!!

Author: Dieter Buerssner

Date: 15:24:40 12/05/03

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On December 05, 2003 at 17:37:50, Tim Foden wrote:

Thanks for your comments (also those, I snipped)

>On December 05, 2003 at 14:33:26, Dieter Buerssner wrote:
>

>>> trans:  probes=1282039  hits=229767 (17.92%)  draft=163348 (12.74%)
>>
>>Do you probe in qsearch?
>
>No.


And later ...

>>163268370 Nodes, 99.50% Leavenodes, 484273 Nodes/sec
>>[                ^^^^^^    ^^ Grrr ..]
>
>:)  In GLC this bit (2.1% / 97.9%) gives the % of normal nodes / % of q-nodes.

I snipped too much, and now I am too lazy, to write it again. These numbers seem
not to fit. Your search showed about 10 times more nodes than HT probes. Here it
is a factor of 50 between qnodes and "normal" nodes ...

>This position is simple a q-search killer!

Sure

>I've experimented with other ways, but so far this is the best I've found in
>GLC.  I still want to experiment with some more though (e.g. what about storing
>best 2 moves??, or 3 hash entries in 32 bytes??).

Without having tried it, I would suspect that having two scores/bounds is more
promising. Your fail high ratios were not bad - would you really expect to make
this much better by having 2 moves to try?

>I would certainly seem to make sense to have all the records for an index be
>bunched close together (rather than in separate tables) so only one read is
>needed... this is still on my todo list!

It should not be difficult to change. I had 2 tables for a while (very similar
to what you described). I think it was less than 2 hours of programming to get
the "3-entries-in-one-table" approach to work. Performance hit was not high,
however (I had expected more). But it was also on a slow computer (perhaps K6-2
233, perhaps even on 486), so on current hardware, it could be more significant.

Cheers,
Dieter




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