Author: Ulrich Tuerke
Date: 00:42:58 04/21/99
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On April 20, 1999 at 15:55:37, Alex Boby wrote: > > Hey guys,... I think the intent of the Principle Variation Search is to >search it first and thus establish the best alpha/beta values for maximum >pruning. > What I don't understand is how to get the search to return a whole PV >instead of just the best move at ply 1. I currently just use full width >alpha/beta minimax and I think that adding PV would be a great improvement for >move ordering. Any help would be much appreciated. I think that PV search usually means something different: on each node, the 1st move of the current move list is searched with the usual alpha-beta aspiration window, the remaining moves are searched using a minimum window around beta. This will be sufficient to refute these moves unless one of these fails high; then a verification search must be performed. In general, this algorithm generates smaller trees. IMO in practice, there are also some draw-backs because of additional alpha beta dependences of the search. BTW, there are many articles about PV search, for instance the one by Donninger in the ICCA journal a few years ago, also giving pseudo code. Uli > >A Boby.
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