Author: Andrew Williams
Date: 16:42:34 09/15/99
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On September 15, 1999 at 17:12:16, Dan Homan wrote: >I was reading the crafty source again the other day and noticed that >Bob has a special function to improve the move ordering at the root >of the search. > >I really didn't feel like writing such a function last night, but I >thought instead to use the values returned by the search itself to >improve the move ordering at the root. I know that I only get an >accurate value for the best move, but I thought that my fail-soft >search might return useful numbers for the other moves as well.... > >Implementing this was pretty quick and easy: there were a couple >of pit falls, but the total changes were about 5 lines of code. >Previously I simply used the same move ordering at the root that I >use at all other nodes. > >The improvement was amazing! I got a full ply in many positions and >about a half-ply in many more. It improved my solution times on WAC >noticably and seems even better in quiet positions. > >I know that my solution was a quick kludge, so I am wondering what >other people do for move ordering at the root of the search. > > - Dan Hi Dan, This is what I used to do. (I'm also using fail-soft). It's one of those things that shouldn't really work, but seems to do very well. However, I later changed it to use the number of nodes in the sub-tree to order root moves. If I recall, this made very little difference to my program's performance; I just prefer this, because I know why it should work. Andrew
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