Persistent homology of unweighted complex networks via discrete Morse theory
We present a new method based on discrete Morse theory to study topological properties of unweighted and undirected networks using persistent homology. Leveraging on the features of discrete Morse theory, our method produces a discrete Morse function that assigns weights to vertices, edges, triangles and higher-dimensional simplices in the clique complex of a graph in a concordant fashion. Importantly, our method not only captures the topology of the clique complex of such graphs via the concept of critical simplices, but also achieves close to the theoretical minimum number of critical simplices in several analyzed model and real networks. This leads to a reduced filtration scheme based on the subsequence of the corresponding critical weights. We have employed our new method to explore persistent homology of several unweighted model and real-world networks. We show that the persistence diagrams from our method can distinguish between the topology of different types of model and real networks. In summary, our method based on discrete Morse theory further increases the applicability of persistent homology to investigate global topology of complex networks.
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