Author: Sune Fischer
Date: 04:46:09 07/20/02
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On July 20, 2002 at 06:59:50, Uri Blass wrote: >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. All right, bad example, the zugzwang is better :) >It is also possible to do a verification search to reduced depth >only to see that you do not miss a big zunzwang. Sure, but given the complexity of their project, perhaps they just tried to keep some things simple. >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 You've lost me there, the history table I use only for move ordering, and the killers, well I try them if they are valid moves, but alpha-beta values? -S.
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