Author: José Carlos
Date: 06:27:01 12/21/01
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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.
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