An Implementation of the Eigenvalue Localization Algorithm for Threshold Graphs in Python

Authors

DOI:

https://doi.org/10.5902/2179460X90148

Keywords:

Threshold graph, Diagonalize algorithm, Implementation, Python

Abstract

A threshold graph of order n may be characterized by a binary sequence (b1, b2, … , bn). We shall present the particulars of the algorithm known as Diagonalize, which provides the location of the eigenvalues of the adjacency matrix of a threshold graph, relying solely on its geometry, without the need for direct manipulations with the matrix itself. We shall observe that the binary characterization is a facilitative tool for a linear implementation of this algorithm in Python.

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Author Biographies

Andressa de Oliveira Eckhardt, Universidade Federal de Santa Maria

Master's student in Mathematics at the University of São Paulo.

João Roberto Lazzarin, Universidade Federal de Santa Maria

Department of Mathematics, professor and researcher 

Fernando Colman Tura, Universidade Federal de Santa Maria

Department of Mathematics, professor and researcher

References

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Jacobs, D. P., Trevisan, V., & Tura, F. (2013). Eigenvalue location in threshold graphs. Linear Algebra and its applications, 439(10):2762–2773. Recovered from: https://www.sciencedirect.com/science/article/pii/S002437951300493X.

Jacobs, D. P., Trevisan, V., & Tura, F. C. (2018). Eigenvalue location in cographs. Discrete Applied Mathematics, 245:220–235. doi: https://doi.org/10.1016/j.dam.2017.02.007.

Lipschutz, S. & Lipson, M. L. (2011). ´Algebra linear. (2nd ed.). Bookman.

Mahadev, N. V. & Peled, U. N. (1995). Threshold graphs and related topics. Elsevier.

Poole, D. (2004). ´Algebra linear. (56th ed.). Cengage Learning.

Tura, F. C. (2013). O espectro de grafos threshold e aplicações (Tese submetida ao Programa de P´os-Graduação em Matem´atica Aplicada). Instituto de Matem´atica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.

Published

2025-02-03

How to Cite

Eckhardt, A. de O., Lazzarin, J. R., & Tura, F. C. (2025). An Implementation of the Eigenvalue Localization Algorithm for Threshold Graphs in Python. Ciência E Natura, 47(esp. 1). https://doi.org/10.5902/2179460X90148

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