Author: Vincent Diepeveen
Date: 16:28:42 02/20/02
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On February 20, 2002 at 16:10:01, Frank Phillips wrote: >On February 20, 2002 at 12:48:06, Steve Maughan wrote: > >>Thanks for the help everyone! >> >>I've implemented the idea I outlined and this has fixed the problem. However >>effectively I ignore possition where I cannot add a hash entry without >>overwriting another. This means that there is currently the possibility of a >>draw not being detected. I'll probably test a rehashing mechanism. >> >>Regards, >> >>Steve > >Just stick the entry in the next available slot (that has a hash signature of >zero). The debug tests I did never showed more than a few re-hashes - once it >was working properly. > >I changed to this method from a simple array list following Bruce's description, >because it seemed so elegant with the possibility of speeding up detection in >the endgame - when the list approach might have many entries to check. > >After falling for the obvious trap of not always removing an entry when exiting >ABsearch() early, it seems to work fine. > >I noticed no significant speed loss (or speed up) in the short middle game test >I use. > >Frank You measured pretty bad then depending upon hashtable size. An array that gets read within 1 cache line and is already within L1 or L2 is kicking the hell out of this hashtable approach.
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