Author: Ed Schröder
Date: 20:59:14 11/28/00
Go up one level in this thread
On November 28, 2000 at 18:38:45, Bruce Moreland wrote: >On November 28, 2000 at 18:20:01, Will Singleton wrote: > >>On November 28, 2000 at 16:06:11, Bruce Moreland wrote: >> >>>On November 28, 2000 at 14:06:27, Andrew Williams wrote: >>> >>>>On November 28, 2000 at 12:52:57, Scott Gasch wrote: >>>> >>>>>Hi, >>>>> >>>>>I posted a couple of messages about move ordering yesterday and wanted to share >>>>>some results from my (limited) testing. I ended up implementing the suggested >>>>>"apparently losing captures" (MVV/LVA) after all others order. In one test >>>>>position this resulted in a tree 200k nodes larger at 8 ply but in two others it >>>>>resulted in a marginally smaller (under 40k nodes) tree at 8 ply. I will do >>>>>more testing on this matter but it may be a moot point because I intend to write >>>>>a SEE pretty soon. >>>>> >>>>>I also did some experimenting with ordering captures that take the last moved >>>>>enemy piece. At low search depth this seems to make some difference but at >>>>>higher depth this heuristic actually grew the tree in all three test positions > I tried. >>>>> >>>>>I also did some playing with history weight and settled on hist[x][y] += (2 << >>>>>depth). >>>> >>>>I use history[whoseTurn][frsq][tosq] += (depthremaining*depthremaining) >>>>I have a separate table for white and black. Every few plies I divide >>>>this number back by a lot (can't remember how much or how often). >>> >>>Why does everyone think that a move that cuts off after a deep search is more >>>likely to produce cutoffs elsewhere in the tree, than one that cuts off after a >>>shallow search? >>> >>>That multiplication is expensive. Does it achieve anything? >>> >>>bruce >> >>How expensive? I've got multiplications and divisions all over my program. I >>never thought it would amount to more than a few nps. >> >>Will > >Good question, and I don't know. The ratio between multiply and add has been >reducing during the past few years, so it used to be a bigger deal. > >It's hard for me to know for sure because there is only one "div" in Ferret core >code and no multiplies. > >bruce Especially multiplies has been improved dramatically in the latest generation of processors. Nowadays it is hardly an issue anymore. I still use << where ever I can but I have no problems to use * so now and then. Ed
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