Author: Uri Blass
Date: 02:24:47 09/01/02
Go up one level in this thread
On September 01, 2002 at 04:40:52, Tony Werten wrote: >On August 31, 2002 at 18:56:52, Uri Blass wrote: > >>On August 31, 2002 at 18:04:27, Tony Werten wrote: >> >>>On August 31, 2002 at 16:15:01, Bas Hamstra wrote: >>> >>>>On August 30, 2002 at 12:30:32, Tony Werten wrote: >>>> >>>>>On August 30, 2002 at 11:27:42, David Hanley wrote: >>>>> >>>>>>So, you do: >>>>>> >>>>>>hash >>>>>>killers >>>>>>captures >>>>>> >>>>>>do you sort captures at all? >>>>> >>>>>Yes, MVV/LVA. >>>>> >>>>>so: >>>>>Hash >>>>>Captures >>>>>Killers >>>>>Rest >>>>> >>>>>XiniX isn't really fast so most of the time I get a bestmove from hashtable ( >>>>>not very much overwritten entries ) >>>>>In addition; since I threw out aspiration search as well I seem to be having >>>>>more bestmoves in the table. >>>>> >>>>>Tony >>>> >>>>Heyyy Tony! :-) >>>> >>>>Just for a comparison: >>>> >>>>- Well, aspiration we agree. >>>>- History I'm not sure, though I still use it. Some say piece square sorting is >>>>a good alternative. >>> >>>I don't use that right now but am quite suprised of my good branching factor. >>>There still must be some room for improvement. >>> >>>>- FP I don't believe in. You? >>> >>>FP by definition can only save nodes when it's incorrect, so I threw it out. >> >>I do not understand. >> >>Do you mean that pruning based on evaluation,remaining depth and other >>conditions is not FP. >> >>If it is not FP then what is FP? > >I'm quite sure (from previous talks with Bas ) he was talking about futility >pruning wich is wrong by nature. > >FP prunes the last move ( before quiescence ) when the score is a certain margin >below alpha. > >Now suppose FP is right but we don't prune. What happens ? We go to quiescence; >evaluate; get a score above beta; and cutoff. So no nodes saved. I know that Bas search checks in the first plies of the qsearch and it is clear that even if the score is abbove beta you do not get cutoff when the king is in check. It is possible to generalize the idea for other cases when the side to move is in trouble so it is not clear that no nodes saved. > >FP can only save nodes when we would otherwise spend time in quiescence; ie >score is not above beta ie fp was wrong. > >People who report big wins with fp probably have an "inc(nodecounter)" in the >top of quiescence, wich doesn't get called when pruning. > >Tony > >PS I'm talking about nodecounts here not time. Time and not nodes is the important thing for games so even if you do not save nodes it does not mean that futility pruning is wrong. Uri
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.