The largest eigenvalue of C₄^--free signed graphs

2023/09/08 by Yongang Wang, Huiqiu Lin, Wang, Yongang +1
Materials Science · Mathematics · #Combinatorics (math.CO) #FOS: Mathematics #Graph theory and applications #Magnetism in coordination complexes #Spectral Theory in Mathematical Physics

paper · pdf · doi:10.48550/arxiv.2309.04101

openalex publication_date 2023/09/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Let C_k^- be the set of all negative C_k. For odd cycle, Wang, Hou and Li [29] gave a spectral condition for the existence of negative C₃ in unbalanced signed graphs. For even cycle, we determine the maximum index among all C₄^--free unbalanced signed graphs and completely characterize the extremal signed graph in this paper. This could be regarded as a signed graph version of the results by Nikiforov [23] and Zhai and Wang [37].

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