Author: Larry Griffiths
Date: 09:47:18 02/01/01
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On January 31, 2001 at 11:18:56, Robert Hyatt wrote: >On January 31, 2001 at 03:29:12, Severi Salminen wrote: > >>>There are two terms that are intermixed often: >>> >>>1. "branching factor" usually means the average number of branches from a >>>node, which for chess averages 35-38 (depending on who you believe) for the >>>whole game. >>>2. "effective branching factor" is roughly calculated as you mentioned. IE >>>nodes for iteration N-1 divided into nodes for iteration N. Or you can use >>>the time. >> >>Ok, now I know the terms. Case 2 is what I indeed meant. >> >>What equation do you use for EBF calculation. I just thought that maybe one >>should not use the number of nodes in the equation I gave, but the number of >>leaf nodes. >> >>root_moves*EBF^(DEPTH-1)=leaf_nodes (not total nodes, I think) >> >>In initial position you have >> >>20*20^(2-1)=400 which is the number of leaves in ply 2. >> >>Using this I have EBF (in Vincent's position) of 3.8. So I still have to improve >>:) >> >>Severi > > >Since nodes per second is fairly constant for a program, you can either >use nodes(ply)/nodes(ply-1) or time(ply)/time(ply-1). Those two numbers >should be pretty similar. > >doing it for leaf positions should also result in fairly comparable numbers, >although search extensions can affect this. I would just use _all_ nodes >to keep it simple and to remain compatible with what others quote. Bob, Severi gave me this formula earlier. ebf=pow(leaf_nodes/legal_root_moves, 1/(DEPTH-1)); Are you suggesting that it should be: ebf=pow(ALL_NODES/legal_root_moves, 1/(DEPTH-1)); Larry.
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