Author: Uri Blass
Date: 09:58:48 04/11/04
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On April 11, 2004 at 08:02:45, Tord Romstad wrote: >On April 11, 2004 at 06:33:10, Daniel Shawul wrote: > >>Hi tord >> >>what does gothmog selectivity 6 means? >>My guess is you do null_move for first 6 plies and >>static eval pruning for the rest. I mean is it like Ed's? > >No, it's not like Ed's at all. It hasn't even got anything to do with plies. >The 'selectivity' >parameter controls one of the criterions which are used to determine whether a >move >should be searched to reduced depth. The first three moves at all nodes in the >main >search are (almost) always searched to full depth. All remaining moves are >candidates >for reductions. For each move, I first check whether it is a capture, check, or >some other >kind of interesting move. If the move does not appear to be interesting at all, >I do one >final test before I decide to reduce it: > > if(History[Compress[m->from]][Compress[m->to]] < > (Nodes >> (20-EngineOptions.selectivity))) > return 1; > >As you can see, I compare the history counter of the move (i.e. the number of >times >the move has failed high in the past) to the number of nodes searched. If the >move has >almost never worked before, it is also not likely to work this time. I also prune based on history but one of my conditions is that faillowcount>128*failhighcount and I do not use number of nodes. I never tried your way because it seemed more logical for me to compare number of failhigh with number of faillow and not number pf failhigh with number of nodes. Uri
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