Computer Chess Club Archives




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

Author: Peter W. Gillgasch

Date: 17:28:02 01/26/00

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On January 26, 2000 at 13:24:21, Ed Schröder wrote:

>>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:

>>>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

In that case it was Don Beal who has mixed you up with somebody else
since the technical description of the participants of an early 90ties
WMCC (Toronto I believe) has a photo of Mr Louwmann and the description
said that moves are generated "one at a time rather than all and sort".
Your ARM was the fastest in the tourney :)

-- Peter

>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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