Author: José Carlos
Date: 10:24:43 09/16/99
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On September 16, 1999 at 06:21:26, Peter McKenzie wrote: >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? I do something similar: I assign the scores for the moves while I generate them (depending on the piece moved, the captured piece, etc...) with a special score for the PV move, that is bigger than the rest. So, at the begining of each ply, I sort the moves by that score. When a new better move is found, it receives the PV score, as the rest of the PV moves. José C. > >> >>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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