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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
>superior.

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.
>
>Ed
>
>>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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