Author: Bas Hamstra
Date: 07:13:29 10/08/99
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On October 07, 1999 at 18:42:35, William Bryant wrote: >Bob has said on may occasions that he puts the pv into the hash table before >each search to improve move ordering and efficiency. > >Trial and error has gotten me close to succeeding in this but a few questions. > >1. I stuff the PV at the start of each iteration. > Now, do you restuff it if a search fails high with a new root move? > If it fails high with the original root move? > If it fails low and you are going to research every move all over again? I am experimenting with this too. I do it when it fails low and I have to research everything over. If I don't do this it takes much longer to get a new PV. I don't have internal deepening yet, maybe that is better. But for me it works better than doing nothing. I just want it to play a fairly good line first, even if its not the best. >2. What values do you use for the hash table entry. > I have been placing each move in as follows: > flag == exact > depth == 0 > score == pv score following the last iteration > bestmove == pv move. > > Note: we want the best move, but not to generate a premature cutoff so > I set depth to 0. This means, that the rest of the entry except the > bestmove will be not be used. > > Should I be using alpha instead? I have a flag PVMOVE. That means the HashMove will be played first, but no score will ever be read from the record. >3. In the root search, I don't probe the hash table, so there is no bestmove. > I use the pv move in this case. > >4. In the QSearch, where I don't probe the hash table, do you still check to see if any of the captures are part of the pv, or simply sort them all in the standard way? I don't update PV's in the QSearch, so the latter. >I am concerned that I may have a few bugs, because I am not getting the >performance that I had by searching the pv move and then the hash table move. Regards, Bas Hamstra. >Thanks in advance. > >William >wbryant@ix.netcom.com
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