License: Creative Commons Attribution 3.0 Unported license (CC-BY 3.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.MFCS.2018.68
URN: urn:nbn:de:0030-drops-96503
URL: https://drops.dagstuhl.de/opus/volltexte/2018/9650/
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Hell, Pavol ; Huang, Jing ; McConnell, Ross M. ; Rafiey, Arash

Interval-Like Graphs and Digraphs

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LIPIcs-MFCS-2018-68.pdf (0.4 MB)


Abstract

We unify several seemingly different graph and digraph classes under one umbrella. These classes are all, broadly speaking, different generalizations of interval graphs, and include, in addition to interval graphs, adjusted interval digraphs, threshold graphs, complements of threshold tolerance graphs (known as `co-TT' graphs), bipartite interval containment graphs, bipartite co-circular arc graphs, and two-directional orthogonal ray graphs. (The last three classes coincide, but have been investigated in different contexts.) This common view is made possible by introducing reflexive relationships (loops) into the analysis. We also show that all the above classes are united by a common ordering characterization, the existence of a min ordering. We propose a common generalization of all these graph and digraph classes, namely signed-interval digraphs, and show that they are precisely the digraphs that are characterized by the existence of a min ordering. We also offer an alternative geometric characterization of these digraphs. For most of the above graph and digraph classes, we show that they are exactly those signed-interval digraphs that satisfy a suitable natural restriction on the digraph, like having a loop on every vertex, or having a symmetric edge-set, or being bipartite. For instance, co-TT graphs are precisely those signed-interval digraphs that have each edge symmetric. We also offer some discussion of future work on recognition algorithms and characterizations.

BibTeX - Entry

@InProceedings{hell_et_al:LIPIcs:2018:9650,
  author =	{Pavol Hell and Jing Huang and Ross M. McConnell and Arash Rafiey},
  title =	{{Interval-Like Graphs and Digraphs}},
  booktitle =	{43rd International Symposium on Mathematical Foundations  of Computer Science (MFCS 2018)},
  pages =	{68:1--68:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-086-6},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{117},
  editor =	{Igor Potapov and Paul Spirakis and James Worrell},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{http://drops.dagstuhl.de/opus/volltexte/2018/9650},
  URN =		{urn:nbn:de:0030-drops-96503},
  doi =		{10.4230/LIPIcs.MFCS.2018.68},
  annote =	{Keywords: graph theory, interval graphs, interval bigraphs, min ordering, co-TT graph}
}

Keywords: graph theory, interval graphs, interval bigraphs, min ordering, co-TT graph
Collection: 43rd International Symposium on Mathematical Foundations of Computer Science (MFCS 2018)
Issue Date: 2018
Date of publication: 27.08.2018


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