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Subject: Re: Generating attack tables: Is this code good?

Author: Tord Romstad

Date: 10:18:02 12/01/03

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On December 01, 2003 at 08:33:56, scott farrell wrote:

>On December 01, 2003 at 06:57:13, Tord Romstad wrote:
>
>>From the initial position, I compute the attack tables about a million
>>times per second with this code.  From WAC1, the rate drops to about
>>700,000 times per second.  The high nodes/second count of Rebel (which
>>has similar tables) makes me believe that it is possible to do this
>>many times faster.
>I am also working on incremental attack tables.
>I also found huge slow downs.

I think you misunderstand.  I have never used incrementally updated
attack tables, only attack tables generated from scratch at every
node.  And I have no idea how much they slow me down, because they
have been in my program since the beginning.

>I am not going to ditch them just yet. I am going to see if I can put the extra
>info to good effect.

Yes, it is very useful several places in the evaluation function.  I
use them to detect mate threats, hanging pieces, compute king safety,
mobility, space, centre control and so on.  There is hardly any
component of my evaluation function which does not make extensive
use of attack tables.

>I think if you can get extra knowledge from the extra work, then you have to not
>use it.
>
>I would be real happy with anything near 1mill/sec - in java I get only about
>200 Knps on an athlon 2Ghz

I don't get anything near 1 million nodes per second.  I meant that with
my new code I can generate the attack tables 1 million times per second
from the opening position.

Actually, my engine searches less than 200 Knps in most middlegame
positions on a PIV 2.4 GHz.  I expect the new engine I am working on
to be even slower when it is finished.

Tord




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