I am reading supplementary information of the paper Activity driven modeling of dynamic networks. It analogys the number of out degree of a activity node by Polya urns problem:
it will equal to the number of different balls extracted from a urn with $N$ balls, performing $Tma_i$ extractions. The probability of extracting $d$ balls will be given by
$$P(d)= \begin{pmatrix} N \\ d \end{pmatrix} p^d(1-p)^{(N-d)}$$
where
$$p=1-(1-\frac{1}{N})^{Tma_i}$$
is the probability of extracting at least one ball in the urn.
I just even dont know why to treated this as Binormial Distribution? How to get the probability of extracting at least one ball in the urn
? What's the solving detail? Thanks for your consideration. Am I clear about my question? Do you need more information for answering my question?
It should looks like:
If there are more than one edges between two nodes, only one edge should be chosen. e6 e1 e8 treated as same ball. For the figure above there should be 9 balls in a urn.