Author: martin fierz
Date: 05:38:46 08/12/04
Go up one level in this thread
On August 12, 2004 at 07:12:08, Tord Romstad wrote: >On August 12, 2004 at 06:40:48, Ross Boyd wrote: > >>Be careful with R=3. It has the potential to make your engine go blind. I lost >>~50 (!!) elo when using pure R=3 in TRACE. I ran the experiment again two days >>ago and it confirmed my previous findings. Currently, pure R=2 works best for >>me... fewer OTB blunders. > >Like virtually everything else in computer chess, this is something which >varies a lot between different engines. In my engine pure R=3 works >*much* better than R=2, and slighly bettter than the classic adaptive >null move pruning technique. Verified null move pruning also didn't >work for me. The only improvement I have found over pure R=3 is a scheme >were I occasionally use R=2 in positions where horizon effect problems >are likely to be a problem (I use the eval to make the decision). > >Part of the reason that R=3 is best for me could be that my engine doesn't >use null moves as much as most other engines. I only do a null move search >when I am reasonably sure of a fail-high, but not quite sure enough to >prune the whole subtree without search. Null move at all nodes more than >doubles my node count, and does not increase the accuracy of my search >noticably. > >Tord hi tord, i'm intrigued by your last sentence - that null move at all nodes more than doubles your node count! i wonder how this is possible at all? why? if i understand what you write you have an oracle which can tell you whether you should do a null-move search at a given node or not. int alphabeta(....)
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