Author: James Swafford
Date: 20:39:41 09/04/99
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On September 04, 1999 at 21:17:00, Pete Galati wrote: >On September 04, 1999 at 19:44:22, Ralf Elvsén wrote: > >>I was thinking of the number of positions one has to search >>in the alpha-beta algoritm. With perfect moveordering the >>number is roughly n^(d/2) , where n = number of moves >>in a position and d = search depth. I know this is a >>simplification of the actual formula but it catches >>the "essence" of it. >> >>With the worst possible >>moveordering it goes like n^d (same as mini-max). >> >>We can summarize this qualitatively as >> >>number of positions = n^(s*d) , where s = 1 for the worst case >>and s = 0.5 for the best case. >> >>Is there anyone out there who has a feel for the actual >>value of s in the programs used today? This would be a measure >>of the quality of the moveordering. I realize that most >>programs have a more complicated search structure with null moves, >>hash tables etc, but it would be interesting to see >>some educated guesses. >> >> Thanks in advance, Ralf > >Just a note since I don't know enough to discuss that, but Inmichess does seam >to use a move order hashtable. It's the only program that I remember that in. > >Pete I think lots of programs store moves in the hash tables. I learned that trick from Crafty a couple years ago. -- James
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