Author: William Bryant
Date: 15:42:35 10/07/99
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? By the time it has failed high or low, the hash table has been rearranged a bit. 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? 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 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. Thanks in advance. William wbryant@ix.netcom.com
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