Author: Andrew Williams
Date: 17:57:59 09/11/99
Go up one level in this thread
On September 11, 1999 at 18:01:30, Alessandro Damiani wrote: >On September 11, 1999 at 17:58:59, James Robertson wrote: > >>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? >>> >>>Alessandro >> >>History didn't help me at all either. I just ended up with a lot lower NPS.... >> >>James > >Am I the last one with history heuristic here? :-) > >Alessandro Nope! PostModernist has history and killers. But it's several months since I played with these; since it is easy to mess around with them, maybe I'll have a look to make sure they are still pulling their weight. Andrew
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