Computer Chess Club Archives




Subject: Re: DB NPS (anyone know the position used)?

Author: Ed Schröder

Date: 10:24:21 01/26/00

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>Posted by Peter W. Gillgasch on January 26, 2000 at 09:18:55:
>In Reply to: Re: DB NPS (anyone know the position used)? posted by Ed
>Schröder on January 26, 2000 at 03:07:42:
>On January 26, 2000 at 03:07:42, Ed Schröder wrote:
>>On January 25, 2000 at 23:57:33, Ernst A. Heinz wrote:
>>>> In a one by one setting it does not matter at all.
>>>Still not convinced: a quiescence node that produces a direct
>>>"stand pat" cutoff obviously generates less work than one
>>>which fails to do so -- even in hardware!  *** QED ***
>>>Or am I missing something?
>>Something else... I always wondered about this free 4-ply evaluation. I
>>can understand that evaluation for the current position done in hardware
>>is possible in a few cycles. I can't understand this also to be true for
>>4 plies as it should involve: search, hash table, q-search etc. In other
>>words a complete chess program.
>Well of course they have a complete chess program for interior nodes
>in hardware as you know. The idea why I think that the position does
>probably not matter too much is because something like 0.07 percent
>of the nodes they do are calculated on the SP and the remaining
>99.93 percent of the nodes are done on the hardware where the transition
>from father to sibling and back has a fixed cost regardless of move
>ordering. I am not saying that the size of the tree is not influenced
>by the position, I am also not saying that the time it takes to complete
>a 4 ply search on the chips does not depend on the position.
>You have experience with one by one move generators since your ARM
>program did that. What is your gut feeling, assuming that all moves
>spend the same time in MakeMove/UnmakeMove (hypothetical) and all
>your move  generators need the same time to produce the next move
>(only a little hypothetical) and you have no instruction count
>differences between the usual case versus the "get out of check" case,
>would you see any major NPS differences between different positions ?

I think you mixed me up with somebody else. I always do and have done
a full move generation and then sort the move list first based on a fast
static evaluation. I have tried the one by one approach but it was not

I suspect the reason is Rebel's expensive evaluation function. If you have
a fast eval NPS will drop considerable doing a full move generation plus a
quick-sort. Having a slow eval like Rebel you hardly see the NPS drop and
you can afford such time consuming things.


>For me it is pretty much constant, ups and downs by maybe 1/6 which
>I attribute to the varying execution times of MakeMove/UnmakeMove and
>the differences between "in check" and "not in check" nodes.
>-- Peter

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