Hi Andreas,
The formula can be found in
Gould, R.V. (1987). Measures of betweenness in non-symmetric networks.
Social Networks, 9, 277-282.

Mark
At 12:16 29.08.01 +0200, you wrote:
>Hi,
>
>as the latest versions of ucinet allow to calculate the betweeness-
>centrality for directional relations, I'looking for a reference where the
>corresponding formulas can be found.
>
>Thanx
>
>Andreas
>***********************************************************
>Andreas Wald
>Lehrstuhl für Politische Wissenschaft I
>Universitaet Mannheim, 68131 Mannheim
>Tel:0621/181-1994 email:[log in to unmask]
>http://www.sowi.uni-mannheim.de/lehrstuehle/lspol1/
>
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