Author: Robert Hyatt
Date: 06:01:17 08/31/01
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On August 31, 2001 at 06:28:25, Steve Maughan wrote: >Bob, > >>Probably better is to save the original alpha/beta values at the root, >>and compare to those. If current alpha = root alpha, and current beta = >>root beta, you are definitely on a PV move search. > >Are you sure this is a definitive test? > >What if the PV from the last iteration fails low at the new deeper tip i.e. does >not adjust alpha or beta. This will then be backed up and alternatives will be >tried that are not part of the original PV. In an exteme case the previous PV >could fail low at the root (which happens reasonably frequently) which will have >meant that every node has been searched with the condition you state. > >Or are you defining a PV search as any search that could result in a PV from the >root? > >Regards, > >Steve Yes to your last question. This is a "hard" search to do, and without good move ordering, it becomes harder still. Hence the internal iterative deepening to help it out. Non-PV nodes are much simpler to search and IID is generally a waste of time for them.
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