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Subject: Re: Rybka nps - 30knps

Author: Ryan B.

Date: 01:06:14 02/07/06

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On February 07, 2006 at 03:21:09, Tord Romstad wrote:

>On February 06, 2006 at 21:47:09, Ryan B. wrote:
>
>>Rather it is to hide extra hidden search or for marketing propaganda
>
>Marketing propaganda?  What does the nodes/second ratio have to do
>with marketing?
>

Many people seem to think that low nps means more chess knowledge in the eval.
You and I may know this is not always the case but many non programmers that buy
chess engines don't.  Note that Vas once posted that he thinks Shredder
manipulates its node count.


>>I do not know but I do know Rybka manipulates its node count.
>
>"Manipulates" is a too negatively loaded word.  It implies something
>dishonest, when it is perfectly possible (and IMHO much more likely)
>doesn't do quite the same kind of work at each node as most other
>programs.
>
>The exact definition of a "node" differs between different programs,
>and even if Rybka uses the most common definition (one node for
>each call to search() or qsearch()) the behavior you observe (high
>tactical strength compared to the N/s, very irregular N/s depending
>on the position) isn't really that strange.  It could be, for instance,
>that Rybka is moving the pieces around a lot on the internal board at
>each node in order to decide just how static the node is, and use this
>to make search decisions.  Such internal, "horizontal" searches at
>each node could easily reduce the N/s count a lot, while preserving
>tactical strength.  It also makes a lot of sense that the N/s is much
>lower in tactically messy positions.
>
>This is just one of many possible explanations, of course.  In any
>case, I think "manipulate" is an unfortunate word to use.
>
>Tord

Sorry if the word "manipulates" sounded negative.  I feel Vas does hide things
in what Rybka does but I do not mean for it to sound negative, it is his right
to do so.  If you know of a similar word that does not imply anything negative
please let me know and I will use the better word in the future.  I don't wish
to offend anyone with my posts.

Ryan



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