Chodrow and Mellor Applied Network Science (2020) 5:9 Applied Network Science https://doi.org/10.1007/s41109-020-0252-y RESEARCH Open Access Annotated hypergraphs: models and applications Philip Chodrow1*† and Andrew Mellor2† *Correspondence:
[email protected] Abstract †Philip Chodrow and Andrew Mellor Hypergraphs offer a natural modeling language for studying polyadic interactions contributed equally to this work. 1Operations Research Center, between sets of entities. Many polyadic interactions are asymmetric, with nodes Massachusetts Institute of playing distinctive roles. In an academic collaboration network, for example, the order Technology, 77 Massachusetts of authors on a paper often reflects the nature of their contributions to the completed Avenue, 02139 Cambridge, MA, USA Full list of author information is work. To model these networks, we introduce annotated hypergraphs as natural available at the end of the article polyadic generalizations of directed graphs. Annotated hypergraphs form a highly general framework for incorporating metadata into polyadic graph models. To facilitate data analysis with annotated hypergraphs, we construct a role-aware configuration null model for these structures and prove an efficient Markov Chain Monte Carlo scheme for sampling from it. We proceed to formulate several metrics and algorithms for the analysis of annotated hypergraphs. Several of these, such as assortativity and modularity, naturally generalize dyadic counterparts. Other metrics, such as local role densities, are unique to the setting of annotated hypergraphs. We illustrate our techniques on six digital social networks, and present a detailed case-study of the Enron email data set. Keywords: Hypergraphs, Null models, Network science, Statistical inference, Community detection Introduction Many data sets of contemporary interest log interactions between sets of entities of vary- ing size.