Author: Ed Schröder
Date: 15:07:42 09/11/99
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On September 11, 1999 at 17:54:55, Alessandro Damiani wrote: >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? That is always the problem with move-ordering ideas as the current way you are doing things is already so good the idea (although good) doesn't work. I try every new idea, you never know. Ed >Alessandro
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