Author: Will Singleton
Date: 08:33:48 12/21/01
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On December 21, 2001 at 09:27:01, José Carlos wrote: >On December 21, 2001 at 02:14:48, Will Singleton wrote: > >>On December 20, 2001 at 18:31:41, Dan Newman wrote: >> >>>>What kind of move you search first in case you don't have the move from >>>>hashtable? >>>> >>>>Ren. >>> >>>If I'm in the PV, I do an internal iterative deepening search and use >>>that move. If not I generate the captures, sort them with a SEE, >>>and use the top one of those. >>> >>>-Dan. >> >>I was thinking of doing IID, and I'm not sure what you mean by the above. Do >>you mean that if the ply 1 move is the pv move, then below that you always do >>IID in any branch? And after the left side, you don't want to spend the effort >>to do IID because of ... ? >> >>Will > > I can't speak for him, but I'll tell you what I do: > I have 3 different "alphabetas": AB, AB_PV, and QSearch. In the root, I first >call AB_PV (which implements IID). For every 1st move, AB_PV calls AB_PV. For >the rest, it calls AB. AB allways calls AB. > When AB_PV calls AB, and it returns a score above alpha (which is the only >bound I pass to AB), I open the window again and call AB_PV to see if this is >really a PV move. > When depth=0, they both call QSearch. > So I don't use IID in the whole left branch of the tree, but only in the "real >PV nodes". > The reason is to apply it only on nodes that are searched with an open window >(BTW, I don't do any prunning in that nodes, because I expect them to be the >PV!). For the rest of the tree, I don't need "the best move", just a "good >enough move", that's why I don't bother to do IID there. > > José C. OK, interesting. Is the benefit significant?
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