Author: Uri Blass
Date: 03:59:50 07/20/02
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On July 20, 2002 at 06:43:44, Sune Fischer wrote: >On July 20, 2002 at 02:39:45, Uri Blass wrote: >>It is possible that they could get 2 productive changes: >> >>1)Add null move pruning >>2)Not use the singular extensions. >> >>It is possible that 2 is not productive without 1 and >>if they did not start by testing 2, they got the wrong conclusions. >> >>Did somebody try to test crafty with their algorithm >>(no null move pruning and singular extensions)? >> >>I guess that it is going to be clearly weaker than >>the Crafty of today at 120/40 time control. >> >>Uri > >I think IBM was playing it safe. >They could have taken more chances, adding nullmove probably would have made it >even stronger, but imagine the embarrasment for them if it failed to see a >simple combination like a mate in 1 :) I do not see how you can miss a mate in 1 with null move. You can miss mate in 2 but not mate in 1. It is also possible to do a verification search to reduced depth only to see that you do not miss a big zunzwang. The problem here is that changing the alpha and the beta value can give you wrong information in the history tables and in the killer moves so I may need to do a special search to reduced depth without updating the killer move and the history tables. Uri
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