Author: Peter McKenzie
Date: 03:21:26 09/16/99
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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. Here is how I handle move ordering at the root: - Before doing any searching I use my normal move ordering function to assign a 'move ordering score' to each move. - Then I completely sort the move list. Thats all the move ordering I do except that when a new best move is found at the root, it is moved to the front of the move list and all the other moves are shuffled down. Do you do this? > >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. That does sound pretty amazing. I just ran a quick test: I added in sorting the movelist by the scores. I didn't notice any real improvement. > >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
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