Author: Robert Hyatt
Date: 04:55:56 09/14/99
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On September 14, 1999 at 04:07:18, Bas Hamstra wrote: >It seems I got PVS working. In comparison to simple alphabeta I get mixed >results. I have seen positions where PVS does 20% less nodes than ab (starting >position). However I have also seen (tactical) positions where PVS does do more >nodes than ab. I am trying to find out how that's possible, but didn't have >enough time. this is normal and correct. In tactical positions, your move ordering is wrong. And you first search the wrong move with alpha,alpha+1, then you have to re-search that move with alpha,beta to get the right value. When move ordering is good, PVS works well. When it is wrong, it takes more nodes. Of course, you play more non-tactical moves in a real game, and the gains outweigh the losses... > >The impression is that pvs is just more sensitive to good moveordering than ab. > >I see that iterative deepening in Crafty. How important is it? > > >Regards, >Bas Hamstra.
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