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Re: [igraph] about ba.game
From: |
Tamas Nepusz |
Subject: |
Re: [igraph] about ba.game |
Date: |
Tue, 5 Jan 2010 20:50:08 +0100 |
Hi,
Yes, there is a theoretical relation between the "power" parameter and the
exponent of the fitted power law distribution. I think it is described in one
of the original Barabasi papers about the model, not sure where and I don't
have my reference list with me right now. However, this relation holds only for
infinite networks -- for graphs with only a few thousand nodes, there is a
significant finite size effect which may distort the "measured" exponent of the
power law. The larger your networks are, the smaller the difference, but it is
still there.
--
Tamas
On 2010.01.05., at 14:33, gunce orman wrote:
> Hello,
>
> I use ba.game funciton to create a scale free network. And then I'm trying
> to calculate the exponent of power law for the different value of the
> parameter "power" of ba.game... Is there any explication of the relation
> between that power parameter ( the alpha exponent of the choosing the
> vertices) and the gamma ( the exponent of the power low of the degrees) ???
>
> If i'm not wrong, for power=1, normally gamma must be 3, because it is linear
> preferential attachement. But when I produce a set of network for power=1 and
> try to find their gamma values by using power.low.fit(), I have many
> different values than 3... Am I doing something wrong???
>
> Thank you very much
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