In this paper, we present a number of network-analysis algorithms in the
external-memory model. We focus on methods for large naturally sparse graphs,
that is, n-vertex graphs that have O(n) edges and are structured so that this
sparsity property holds for any subgraph of such a graph. We give efficient
external-memory algorithms for the following problems for such graphs: -
Finding an approximate d-degeneracy ordering; - Finding a cycle of length
exactly c; - Enumerating all maximal cliques. Such problems are of interest,
for example, in the analysis of social networks, where they are used to study
network cohesion.Comment: 23 pages, 2 figures. To appear at the 19th Annual European Symposium
on Algorithms (ESA 2011