Hadwiger's conjecture for squares of 2-trees

Chandran, Sunil L and Issac, Davis and Zhou, Sanming (2019) Hadwiger's conjecture for squares of 2-trees. In: EUROPEAN JOURNAL OF COMBINATORICS, 76 . pp. 159-174.

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Abstract

Hadwiger's conjecture asserts that any graph contains a clique minor with order no less than the chromatic number of the graph. We prove that this well-known conjecture is true for all graphs if and only if it is true for squares of split graphs. This observation implies that Hadwiger's conjecture for squares of chordal graphs is as difficult as the general case, since chordal graphs are a superclass of split graphs. Then we consider 2-trees which are a subclass of each of planar graphs, 2-degenerate graphs and chordal graphs. We prove that Hadwiger's conjecture is true for squares of 2-trees. We achieve this by proving the following stronger result: for any 2-tree T, its square T-2 has a clique minor of order chi(T-2) for which each branch set induces a path, where chi(T-2) is the chromatic number of T-2. (C) 2018 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Publication:	EUROPEAN JOURNAL OF COMBINATORICS
Publisher:	ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Additional Information:	Copyright of this article belongs to ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Department/Centre:	Division of Electrical Sciences > Computer Science & Automation
Date Deposited:	10 Feb 2019 08:47
Last Modified:	10 Feb 2019 08:47
URI:	http://eprints.iisc.ac.in/id/eprint/61332

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