{ "id": "1409.6810", "version": "v1", "published": "2014-09-24T03:39:15.000Z", "updated": "2014-09-24T03:39:15.000Z", "title": "The Treewidth of Line Graphs", "authors": [ "Daniel J. Harvey", "David R. Wood" ], "comment": "18 pages (including appendices)", "categories": [ "math.CO" ], "abstract": "The treewidth of a graph is an important invariant in structural and algorithmic graph theory. This paper studies the treewidth of line graphs. We show that determining the treewidth of the line graph of a graph $G$ is equivalent to determining the minimum vertex congestion of an embedding of $G$ into a tree. Using this result, we prove sharp lower bounds in terms of both the minimum degree and average degree of $G$. These results are precise enough to exactly determine the treewidth of the line graph of a complete graph and other interesting examples. We also improve the best known upper bound on the treewidth of a line graph. Analogous results are proved for pathwidth.", "revisions": [ { "version": "v1", "updated": "2014-09-24T03:39:15.000Z" } ], "analyses": { "subjects": [ "05C75", "05C76" ], "keywords": [ "line graph", "minimum vertex congestion", "sharp lower bounds", "algorithmic graph theory", "paper studies" ], "note": { "typesetting": "TeX", "pages": 18, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1409.6810H" } } }