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THanks.  I pretty mush said that.  But the (darn their curiosity!) student wanted to know WHY the negative results appear.


On Mon, Sep 28, 2015 at 3:43 PM, Vincenzo Nicosia <[log in to unmask]> wrote:
On Mon, Sep 28, 2015 at 03:21:31PM -0400, Jordi Comas wrote:


>    So, can someone help me out?  To my eyes, the Bonacich algoritihim sums up
>    the centrality score of each node by weighting each node.  How can and
>    additive series get a negative score?
>    Thanks!
>    Jordi
>    (cookies in the mail for you for good answer.  :) )

The problem is that if \beta is larger than the inverse of the largest
eigenvalue of the adjancency matrix, the sum which defines the
centrality scores does not converge any more. One of the practical
consequences is that the negative values will appear here and there in
your eigenvector, but the basic message is that the results you get
for your centrality scores loose any meaning.



[ Enzo Nicosia - School of Mathematical Sciences - Queen Mary UL ]
[ -- v.nicosia [at] qmul.ac.uk -- katolaz [at] yahoo [dot] it -- ]
[ -- web @QMUL: http://maths.qmul.ac.uk/~vnicosia/index.html  -- ]
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Jordi Comas

"There is nothing so practical as a good theory."  Kurt Lewin

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