Author: Svein Bjørnar Myrvang
Date: 10:24:03 10/03/05
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On October 03, 2005 at 09:20:12, jan willem van drunick wrote:
>Can somebody tell me what the effect is of lowering the default extended
>futility pruning of Fruit 2.2?
>Will the engine play more tactical, and less strategical?
>And when an engine plays more tactical; what will be the effect on the strength
>in general? And vice versa: what is the effect on the strength when the engine
>plays more strategical?
there's no way to know for sure until you've tested it. A lot of the posts on
this forum is about adjustments made to such settings in an attemt to make the
programs stronger vs. other programs. Pruning is not as simple as tactical vs.
strategic play. Lowering the values means more pruning and a more selective
search. It increases maximum search depth and the risk of overlooking someting
important. Raising the values will lead to fewer cutoffs and at some point make
the engine slower than it would have been with no extended futility pruning at
all. In both cases the engines tactical ability suffers. The aim is to find the
golden mean.
>I played some engine-matches between Fruit 2.2. and Shredder 9 (CB)Columbus egg.
>settings (b and d), and it seems that Fruit is playing more active with extended
>futility pruning 45 than the default setting 70.
45 sounds a tad agressive to me, 70 overly cautious. A rule of thumb is:
futility is about the value of a minor piece, extended futility the value of a
rook and razoring ("extended" extended futility) values should be roughly the
value of a queen. The reason why Fruit seems more "active" may be that a deeper
search makes it stronger and able to take to the offensive against opponents
that used to have the edge. It does not change the way Fruit evaluates the
positions.
>But ... I played only a few games; so it's only a first impression. And I am
>addicted to chess, but as far as concerned the technical aspect of computerchess
>I am a 'tabula rasa'.
>Can someone give me some information regarding this subject?
check out http://www.seanet.com/~brucemo/topics/topics.htm
it's a great place to start.
>Thank you in advance.
>
>Kind regards,
>Jan Willem
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