Author: Dan Homan
Date: 05:04:29 09/16/99
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Seems like most people don't see much of an improvement from move ordering at the root (beyond the hash move, of course). I guess I didn't find a silver bullet :) Sorry to have gotten so excited about this and written possibly exagarrated claims.... As I wrote in a post below, I've thought about this and realized that it is possible that the speed up was 'only' 10-20% for me, but because I count a ply as searched when it is completed and a half-ply as searched when the first move is completed, that I noticed many positions that seemed to get an extra half-ply or ply. What I do know is that it was definitely an improvement for me, I got better times and more problems solved on WAC. I also seemed to get deeper-faster on several quiet positions I checked. However, the fact that it was an improvement for me may mean nothing more than 1) I covered up some bug or 2) I had crummy move ordering before. I'll do some more tests and report more information when I have it. - Dan 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
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