Knowledge and Information Systems

, Volume 35, Issue 2, pp 311–343

D-cores: measuring collaboration of directed graphs based on degeneracy

  • Christos Giatsidis
  • Dimitrios M. Thilikos
  • Michalis Vazirgiannis
Regular Paper


Community detection and evaluation is an important task in graph mining. In many cases, a community is defined as a subgraph characterized by dense connections or interactions between its nodes. A variety of measures are proposed to evaluate different quality aspects of such communities—in most cases ignoring the directed nature of edges. In this paper, we introduce novel metrics for evaluating the collaborative nature of directed graphs—a property not captured by the single node metrics or by other established community evaluation metrics. In order to accomplish this objective, we capitalize on the concept of graph degeneracy and define a novel D-core framework, extending the classic graph-theoretic notion of \(k\)-cores for undirected graphs to directed ones. Based on the D-core, which essentially can be seen as a measure of the robustness of a community under degeneracy, we devise a wealth of novel metrics used to evaluate graph collaboration features of directed graphs. We applied the D-core approach on large synthetic and real-world graphs such as Wikipedia, DBLP, and ArXiv and report interesting results at the graph as well at the node level.


Graph mining Community evaluation metrics Degeneracy Directed cores 

Copyright information

© Springer-Verlag London Limited 2012

Authors and Affiliations

  • Christos Giatsidis
    • 1
  • Dimitrios M. Thilikos
    • 2
  • Michalis Vazirgiannis
    • 1
    • 3
    • 4
  1. 1.LIXÉcole PolytechniquePalaiseauFrance
  2. 2.Department of MathematicsNational and Kapodistrian University of AthensAthensGreece
  3. 3.Department of InformaticsAthens University of EconomicsAthensGreece
  4. 4.Télécom ParisTech, LTCIParisFrance

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