Author: Robert Hyatt
Date: 10:00:15 08/23/01
Go up one level in this thread
On August 23, 2001 at 12:44:42, Sune Fischer wrote: >>>I just upgraded my little engine from using a negamx to an alpha-beta algorithm. >> >>Negamax _is_ alpha/beta. It is just re-formulated so that + scores are >>always good for the side on move in the tree. Normal alpha/beta has +=good >>for odd plies, -=good for even plies, which makes the code messier. > >I thought that negamax was minimax, only "re-formulated". > > It is. When I first read your question, I never considered that you would really be doing pure minimax. I caught this a bit later (below) and kept going. >>Normal alpha/beta should give you an effective branching factor of about >>sqrt(x) where x is the effective branching factor of pure minimax. That >>ought to be somewhere around 6-10 max. > >I thought that was a theoretical best and only if I have a perfect moveordering >(which of cause I never do). You can get _very_ close to theoretical best, using the normal move ordering ideas like killers, captures, hash moves, history moves, PV moves, etc... > >>Most everyone uses negamax as the framework. Whether you use simple >>alpha/beta on top of that, or something more sophisticated (I use PVS for >>example) doesn't change the look of the basic search that much. > >Okay thanks.
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