Eigenspaces for \(-2\) in signed line graphs

It is known that \(-2\) appears in the spectrum of a connected signed line graph if and only if its root is either (a) a balanced signed graph, not a tree, that spans a switching of the complete signed graph or (b) an unbalanced simply signed graph, not a unicyclic simply signed graph, that spans...

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Bibliographic Details
Main Author: Zoran Stanić
Format: Article
Language:English
Published: American Journal of Combinatorics 2025-05-01
Series:The American Journal of Combinatorics
Subjects:
Online Access:https://ajcombinatorics.org/ojs/index.php/AmJC/article/view/31
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Summary:It is known that \(-2\) appears in the spectrum of a connected signed line graph if and only if its root is either (a) a balanced signed graph, not a tree, that spans a switching of the complete signed graph or (b) an unbalanced simply signed graph, not a unicyclic simply signed graph, that spans a switching of the signed doubled complete graph. In this paper, we compute the eigenspaces for $-2$ of these signed line graphs. The contribution can be seen as an alternative to [Discrete Appl. Math. 207 (2016) 29--38].
ISSN:2768-4202