Total communicability (Estrada and Hatano 2008; Benzi and Klymko 2013) sums the walks of every length that start at a node, a walk of length \(k\) weighted by \(1/k!\): $$TC(v) = \sum_{w} \left[ e^{A} \right]_{vw} = \sum_{w} \sum_{k = 0}^{\infty} \frac{(A^k)_{vw}}{k!}.$$
Arguments
- x
Network input accepted by
centrality.- ...
Further arguments to
centrality, such asdirectedandnormalized.
Details
\(A\) is the binary adjacency matrix, so edge weights are ignored. On an
undirected network the matrix exponential is formed from the
eigendecomposition of the symmetric \(A\). On a directed network it is
computed by scaling and squaring with a Pade approximation (Moler and Van
Loan 2003), and the scores are the row sums of \(e^{A}\), the
walks that leave each node. directed = FALSE gives the undirected
reading.
References
Estrada, E., & Hatano, N. (2008). Communicability in complex networks. Physical Review E, 77(3), 036111. doi:10.1103/PhysRevE.77.036111 .
Benzi, M., & Klymko, C. (2013). Total communicability as a centrality measure. Journal of Complex Networks, 1(2), 124-149. doi:10.1093/comnet/cnt007 .
Moler, C., & Van Loan, C. (2003). Nineteen dubious ways to compute the exponential of a matrix, twenty-five years later. SIAM Review, 45(1), 3-49. doi:10.1137/S00361445024180 .
