Author: Sune Fischer
Date: 06:06:46 05/07/02
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On May 07, 2002 at 06:24:19, Uri Blass wrote: >I read in bruce moreland's site about hash tables >see http://www.seanet.com/~brucemo/topics/hashing.htm > >I try to use them first in my program only for better order of moves >and I try to use the algorithm that is in that site > >I think that there is some misleading information there > >The function RecordHash includes recording the best move but when the depth is 0 >there is no best move that was leading to the position. In cases where there is no move I store a zero-move, the old move has to be overwritten anyway. >When I use hash tables only for better order of moves then it seems to be >useless to record hash tables when the remaining depth is 0. Yes I think you are right, unless you also hash in the qsearch you would have no idea what kind of result (exact or fail low/high) to store. >I also think that recording hash tables in the last plies is relatively >unimportant at long time control and it may be even better not to try it if I >use the scheme "always replace" because it is more important to remember the >best moves in the first plies. > >Am i right? I believe Vincent said he hashes everything in Diep, if your eval() is very large it may be worth it. A special HT for pawnstructure evaluation is very commen. >I prefer to start with something relatively simple and to check that I have no >bugs and only later to develop it to something more complicated and this is the >reason that I use "always replace" Well start by making sure you key is not corrupted during search (I assume you build it incrementally), nothing will work until that is in order. -S. >changing "always replace" to "only replace" when the remaining depth is big >enough seems to me simple to do when there is no problem to use information in >the hash tables about the best move for future search but replace only when the >depth is the same or bigger can cause problems later if I want to use >information of previous search about the best move because the depth in the >hashtables is wrong. > >Uri
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