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arXiv · 0904.3741

The h-Index of a Graph and its Application to Dynamic Subgraph Statistics

David Eppstein·Emma S. Spiro
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Abstract

We describe a data structure that maintains the number of triangles in a dynamic undirected graph, subject to insertions and deletions of edges and of degree-zero vertices. More generally it can be used to maintain the number of copies of each possible three-vertex subgraph in time O(h) per update, where h is the h-index of the graph, the maximum number such that the graph contains $h$ vertices of degree at least h. We also show how to maintain the h-index itself, and a collection of h high-degree vertices in the graph, in constant time per update. Our data structure has applications in social network analysis using the exponential random graph model (ERGM); its bound of O(h) time per edge is never worse than the Theta(sqrt m) time per edge necessary to list all triangles in a static graph, and is strictly better for graphs obeying a power law degree distribution. In order to better understand the behavior of the h-index statistic and its implications for the performance of our algorithms, we also study the behavior of the h-index on a set of 136 real-world networks.

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David Eppstein, Emma S. Spiro. 2009-04-23. The h-Index of a Graph and its Application to Dynamic Subgraph Statistics. https://doi.org/10.7155/jgaa.00273

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