Author: Alessandro Damiani
Date: 14:54:55 09/11/99
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On September 11, 1999 at 15:56:10, Ed Schröder wrote: >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 I am surprised: history doesn't help? I think that the static ordering is good enough then. Perhaps history is good for those with a bad static ordering, like me? Alessandro
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