Author: Robert Hyatt
Date: 08:18:56 01/31/01
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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.
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