Author: Gerd Isenberg
Date: 03:20:57 02/03/03
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On February 02, 2003 at 09:06:46, Bas Hamstra wrote: >There are some succes stories about replacing nullmove with FH reductions. In >fact what Ed Schroeder does is the same thing, in my opinion. I am interested in >other experiences with this technique. So far I find it disappointing. The idea >is to reduce the search whenever in the FW search the color to move's static >evaluation (minus a static threat evaluation) is already above beta without >having moved. Suppose you combine this with nullmove, and you do a nullmove >first. If the nulmove fails high, you obviously won't profit from FHR. If the >nullmove fails low, what on earth would you reduce the search for??? It can only >be wrong... So to really profit from it, you would have to do FHR first. So if >static-threat > beta, you would reduce the search one ply before doing the >regular nullmove code. A couple of thoughts: in stead of static eval minus >static threat, you might as well do a nullmove+qsearch, I would say. However >neither will be really accurate and you end up using R=4 where you really >shouldn't. Any thought on this? > >Best regards, >Bas. Hi Bas, As far as i remember, the original FHR-approach was intruduced by Rainer Feldmann, one of the authors of Zugzwang (Advances in Computer Chess 96?). It is based on Nullmove observation, but instead of a possibly risky Nullmove cutoff, the search depth was simply reduced by one ply. What success stories do you mean? Regards, Gerd
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