Author: Thomas Mayer
Date: 08:17:43 01/09/02
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Hi David, >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 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. well, my experience with recapture extensions wasn't that good - they let the tree grow extremely with not much effort... There are several ways you can minize the extensions, e.g. you can say: Only extend when you recapture the same piece then the opponent has captured. Or you say you extend only when you are in a specific alpha beta window (I was experimenting with Alpha-200,Beta+200)... There was also the suggestion to extend only when you are in a specific distance to the leaf node, like say 5 halfmoves or 3 halfmoves away from leaf... After all those experiments I was not very happy with the results and throw the extension out (at the moment, things might change... :) -> in some tactics it was a quite good extension, in some positions it sucks totally, simply because there are to many recaptures... Greets, Thomas
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