Author: Ed Schröder
Date: 12:56:10 09/11/99
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On September 11, 1999 at 15:42:03, Robert Hyatt wrote: >On September 11, 1999 at 11:42:29, Ed Schröder wrote: > >>>Posted by Robert Hyatt on September 11, 1999 at 10:19:19: >>> >>>In Reply to: Re: Interesting mate test for hashing posted by Ed Schröder on >>>September 11, 1999 at 01:43:12: >>> >>>On September 11, 1999 at 01:43:12, Ed Schröder wrote: >>> >>>> >>>>Do not underestimate the idea that in case there is no bestmove from the >>>>hash table you do a full static evaluation of all nodes first and based >>>>on that you pick the bestmove as being the first move you are going to >>>>search for this (new) depth. The very early Rebel's (1981) worked that >>>>way and I remember (although the system is very time consuming) it was >>>>superior to all other systems I tried. >>>> >>> >>>I'm not underestimating it. I was simply saying that this approach can >>>be applied when the position is encountered and there is no 'best move' >>>in the hash table. Rather than doing it when the hash entry is stored, >>>and we are not even sure that this hash entry will ever be used again or >>>that it won't be overwritten before it is needed. >> >>Right. >> >>>>I later removed the system because hash tables + bestmove was more powerful >>>>at least for Rebel. But I wouldn't exclude the possibility such a system >>>>can have a positive effect on the speed of the search. >>>> >>>>Actually I didn't remove the system but I replaced it with a faster one >>>>that is: >>>> >>>>- generate all legal moves; >>>>- for all moves do a (very) quick evaluation; >>>>- sort all moves based on the quick evaluation. >>>> >>>>This (move ordering) system (for Rebel) is still superior. >>>> >>>>Ed >>> >>> >>>Do you use killers, history, etc? >> >>Just the normal stuff. >> >>Order... >> >>- hash table move >>- winning captures (ordered by expected material gain) >>- promotion >>- equal captures (QxQ etc) >>- killers (4 of them) >>- remaining moves ordered by the intelligent move generator >> >>The Killer History from Jonathan Schaefer gave no improvement for me. >> >>Ed > > >It probably won't help if you keep 4 killers. I didn't find any improvement >in Cray Blitz either... but I did even more with killers. I tried the current >ply killers then the killers from _other_ plies if they were legal... adding >history did nothing for me... I probably ought to re-check Crafty again as it >might be extra overhead for nothing now... I use 2 killers from the current ply (that's the normal way) and the 2 from 2 plies back. The latter gave me 5%. Ed
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