Author: Christophe Theron
Date: 11:12:23 08/01/04
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On August 01, 2004 at 13:51:47, vladan wrote: > > > > >Hi Remi, > > >"Extender" is Alfa-Beta procedure we use in terminal nodes instead of static >evaluator. Only a fraction of all generated moves are computed (captures, some >checks and promotion moves). It is very important to optimize this procedure as >much as possible. We call this a "quiescence search" or "QSearch". This term has been used for the last 50 years I think. When you publish papers, it is a good idea to use terms that are commonly used in your field of research. Or maybe I do not understand what you extender does? >Hash system used in Axon is simple: > >6 bytes (48 bit): > > >24 bit - fractional position key, >16 bit - best move, >8 bit - other flags. > > >Using this compressed hash system we have tested Axon with 32 million >positions/best moves memory. All nodes (included ones generated by the extender) >could be supplied with best moves efficiently. > > >Of course, 24-bit is not enough to determine positions exactly (like Zobrist >64-bit hash); different positions could generate the same 24-bit hash key. But >those cases (hash failure) are not fatal for searcher - they only could decrease >quality of move ordering. But if the best move is found, Alfa-Beta, Null-Move >and Extender procedures could make a great number of cutoffs. > >This is the main reason why our hash could be used for searcher and not for >draw-detector. If I understand correctly, you use your hash table only for move ordering. You do not use it to produce direct cut-offs. Correct? Christophe > > >Best regards, > >Vladan (Axon programmer)
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