Author: Vincent Diepeveen
Date: 09:13:22 01/09/02
Go up one level in this thread
On January 09, 2002 at 10:15:53, David Rasmussen wrote:
>Some time ago we talked about the recapture extension. Bob's experiments with
>Crafty seemed to show that recapture extension was a bad idea at least for his
>program.
>
>How many people have the recapture extension because they positively believe
>that it is better for their program, and how many has removed it from their
>program because the positively believe that it is bad for their program?
I have it turned off of course.
Recapture extensions never have given me much in practical gameplay,
but for certain testsets they sure work.
Also things are dependant upon 2 other factors whether you can or cannot
use them
- searchdepth/branching factor
- what you do near the leafs (qsearch, nullmove)
Obviously if your branchingfactor is good and therefore you have a good
search depth, then using recapture extensions is a real bad idea.
I guess this is why it doesn't work perfectly for crafty.
If you do a lot in qsearch like me (i do not prune on alfa there, only
beta) then you pick up many tactics there already and there is less need
for extensions plies before that.
Obviously crafty is doing real little in qsearch which means it can use
recaptures if search depth is not the mainfocus, but considering nowadays
hardware it's up to Bob to decide.
>I am sure a lot of people have it or don't have it, but for no specific reason,
>that is, they have not tested the effect of this extension thoroughly.
I have tried them in all different kinds of forms.
- all recaptures
- only piece recaptures of equal pieces
- only pawn recaptures
- only recapturing dependant upon alfa and beta demands like for example
recapturing towards > alfa
And another 100 combinatoins of that with also sometimes other conditions.
But in the end it never worked.
>/David
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