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MiS Preprint

On the spectrum of the normalized Laplacian for signed graphs: Interlacing, contraction, and replication

Fatihcan M. Atay and Hande Tuncel


We consider the normalized Laplacian matrix for signed graphs and derive interlacing results for its spectrum. In particular, we investigate the effects of several basic graph operations, such as edge removal and addition and vertex contraction, on the Laplacian eigenvalues. We also study vertex replication, whereby a vertex in the graph is duplicated together with its neighboring relations. This operation causes the generation of a Laplacian eigenvalue equal to one. We further generalize to the replication of motifs, i.e. certain small subgraphs, and show that the resulting signed graph has an eigenvalue 1 whenever the motif itself has eigenvalue 1.

May 31, 2013
Jun 3, 2013
MSC Codes:
05C50, 05C22, 15A18, 05C76
Signed graph, interlacing, normalized Laplacian, contraction, replication, dominating set

Related publications

2014 Repository Open Access
Fatihcan M. Atay and Hande Tuncel

On the spectrum of the normalized Laplacian for signed graphs : interlacing, contraction, and replication

In: Linear algebra and its applications, 442 (2014), pp. 165-177