Author: Frank Schneider
Date: 23:50:42 12/26/99
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On December 27, 1999 at 00:07:47, William Bryant wrote: >If your search fails low on the root PV move. >(IE. the full alpha beta window for the PV move returns a score <= alpha >and nothing is backed up into the PV array). > >Do you? > >1) Stop PVS and search the rest of the root moves for this iteration with a > full alpha beta window? > >2) Stop PVS until at least one move for this iteration falls into the alpha > beta window. If no moves fall into the window, research the whole > iteration with a lower window. (fail low). This means that you may end up > searching every move with a full alpha beta window which would take more > time before the fail low occurs. > >3) Stop now and lower the window and research with PVS. > This is what Gromit does: it researches the first move (which had a score <= alpha) with a bigger window (-infinity, score). I think 4 is an interesting alternative. Frank >4) Do Nothing? > Continue the rest of the root moves within the -alpha-1, -alpha PVS window. > Only search moves outside the PVS window for the rest of this iteration > if they return a score > alpha on the PVS search. Hope that if the > every root move is going to fail low, that this will speed up the > search until the window is lower. > >5) Suggest something better. > >Fail low on the root move seem to bring my search to a crawl and I'm looking >for a way to be more efficient. > >Thanks in advance. > >William >wbryant@ix.netcom.com
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