Author: Vincent Diepeveen
Date: 06:47:42 05/13/02
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On May 13, 2002 at 09:43:03, Vladimir Medvedev wrote: > >> - did you check the key with a non incremental verification function? > >Yes, I have checked it and compared incremental and non-incremental variants >carefully. Captures, en passants, promotions and castling are processed >correctly :) > >> - do you store things like >> a) bound >> b) depthleft to search >> c) score of search > >I store the following set of data in each hash entry: > >* full 64-bit key >* depth >* entry type (alpha, beta or exact eval.) >* evaluation you must store the search score, so alfa or beta. Not the evaluation. >I write new entries to hashtable after getting exact score from Quiesce(), or >when doing beta cut-off, or when returning alpha from alpha node. > >HT seems to work correctly during one iteration. It speeds up my engine up to 20 >times in elementary ending K+P vs. K (and plays right moves), and number of >nodes diminishes from ~millions to ~100K while searching on ply 13 in this >ending. > >> >>Another thing can cause huge instabilities, that's if you forward prune >>and combine that with hashtables and nullmove. >> > >No, I do not implement null move yet. The only trick is "if(inCheck) depth++" >while alpha-beta search, but I record depth into HT correctly. > >My HT implementation is very similar to described at >http://www.seanet.com/~brucemo/topics/
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