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In this paper by Kempe-Kleinberg-Tardos, the Authors propose a greedy algorithms based on submodular functions to determine the $k$ most influential nodes in a graph, with applications to social networks.

Basically the algorithm goes as follows:

  1. $S = {\rm empty~set}$
  2. pick the node with highest individual influence, call it $v_1$; $S = S\cup v_1$
  3. remove $v_1$ and all edges connecting $v_1$ to the rest of the network
  4. repeat until $S$ has $k$ vertices

I have two questions about influential nodes in social networks.
a) Is there any algorithm to find the solution, or an approximation of it in a decentralized fashion?
b) Did anyone apply other algorithms, such as Page-Rank and similar, to solve the same problem?

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  • $\begingroup$ How do you define an "influential" node? $\endgroup$ – Timothy Sun Sep 8 '11 at 22:57
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    $\begingroup$ according to the paper, each link is defined with a probability to successfully transmit a message from one node to another. The objective is to find the subset of nodes that will deliver a message to the largest number of nodes, on expectation. $\endgroup$ – Bob Sep 9 '11 at 0:15
  • $\begingroup$ Regarding distributed algorithms: In general, any problem of the form "find $k$ best nodes" is inherently global; it cannot be solved much faster than in time $D$, where $D$ is the diameter of the graph. To see this, consider the case of $k = 1$ and connect two "good" nodes with a long path; to determine which of the good nodes is best, you need to propagate information for order of $D$ hops. $\endgroup$ – Jukka Suomela Oct 12 '11 at 23:29
  • $\begingroup$ I understand that. My concern was if there is, at least, a suboptimal algorithm to approximate the optimal solution. $\endgroup$ – Bob Oct 14 '11 at 23:12
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Decentralized algorithms for variants of this problem have been published in A distributed and privacy preserving algorithm for identifying information hubs in social networks and Social Influence Analysis in Large-scale Networks.

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how about these? Bringing Pagerank to the Citation Analysis by Ma, Guan, Zhao

PageRank for ranking authors in co-citation network Ding, Yan, Frazho, Caverlee

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