Author: Steve Maughan
Date: 03:28:42 03/09/99
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On March 09, 1999 at 03:46:16, Alessandro Damiani wrote: Allessandro Thanks for the feedback - I'm afraid you lost me with some of it! >Hi! > >I have changed from Alpha-Beta to NegaScout because of Singular Extensions. The >big advantage of NegaScout is that at the root of the search 'tree' you know >which move will be the PV-move: I don't understand!? Surely with Alpha-Beta and iterative deepening you also know which move will be the PV move at any point? >if the null-window test tells you that the >current move is better than the best move it will be researched and get the best >move. So NegaScout gives you more information about the pv than Alpha-Beta. If >you use heuristics that change the length of the paths of the 'tree' then you >will notice search anomalies (contradictions between a null-window test and a >research). To avoid this I have removed the fail-soft part of NegaScout, >accepting the consequences. > >In Fortress I only use Singular Extensions at pv-nodes. Using NegaScout the >program accepts a pv only if all singular moves on it are searched deeper and is >still best. Of course the cost is high! But I hope that a better forward pruning >will change that (the current forward pruning is too risky). > What do you mean by "accepts a pv only if all singular moves on it are searched deeper and is still best"? How are you defining what is and is not a singular move? >Alessandro Regards Steve Maughan
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