Author: Ernst A. Heinz
Date: 09:27:39 08/23/00
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Hi Christophe, >I have never understood this "not re-search in the last plies" trick. Obviously >it does not work for the reasons you have given, but I think it also simply >does >not work if you use a QSearch. I suspect this optimization works only when you >do not have a QSearch, and you consider the nodes at the horizon to be terminal >nodes. Because in this case the score you have got with the null window cannot >change after the re-search with the full window. > >If somebody understands it in a different way, I'm interested to hear about the >explanation... The "trick" has nothing to do with quiescence search which actually is an expensive (non-static) evaluation function. That is why I use the general abstraction "horizon_score" for it in my book. The negascout "trick" only works for _real_ fixed-depth searches _without_ any depth extensions and reductions. As soon as you do varibale-depth searches with only nominally fixed depths, the research is always compulsory and the negascout "trick" does not work because the path lengths below the node in question may be much longer than 3 plies until they finally reach the horizon. =Ernst=
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