Author: Volker Böhm
Date: 23:26:18 05/22/04
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On May 22, 2004 at 20:17:45, Robert Hyatt wrote: >On May 22, 2004 at 19:54:08, Volker Böhm wrote: > >>Hi, >> >>trying to understand why my IID does not work, I read crafty´s IID code. (I´ve >>solved my problem, in crafty the solution is hidden in the "do_null" flag as it >>is used as a "do_iid" flag too). >> >>But I have one question left: >> >>Crafty does IID only if Alpha == RootAlpha && Beta == RootBeta. >>In IID Crafty calls "search" with current Alpha, Beta window and depth - 2. >> >>When IID search fails low crafty searches again with window -MATE, Beta. With >>this new window crafty would not be able to "iterative deepening" as when >>"search" is called with window (-MATE, Beta) he will not make IID most of the >>times as -MATE is not a Rootwindow-Bound. >> >>For me it would make more sence to change the if statement to Alpha <= RootAlpha >>&& Beta >= RootBeta. >> >>Am I missing something? >> >>Greetings Volker > >Yes. I only want to do a _couple_ of IID searches during a single normal >search. Not hundreds or thousands. If the IID tst is done and either alpha or >beta is not the same as at the root, no IID is done there... while searching alpha will only get larger, beta will only get smaller. Thus alpha <= RootAlpha (or alpha <= -RootBeta when other side to move) nearly allways get the same result as alpha == RootAlpha (or alpha <= -RootBeta when other side to move). The only difference is in the rare case of a IID research with (-MATE, Beta). Thus I don´t think your answer fits to my question.
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