Abstract
Motivated by conjectures of Karloff, and Van Dam and Sotirov on the smallest eigenvalues of Johnson and Hamming graphs, Brouwer, Cioabă, Ihringer and McGinnis obtained some new results involving the eigenvalues of various graphs coming from association schemes and posed some conjectures related to the eigenvalues of Grassmann graphs, Bilinear forms graphs and Hermitian forms graphs. In this paper, we prove some of their conjectures.
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Notes
The details of these calculations can be found on the webpage https://github.com/Himanshugupta23/Hermitian-Graph-Eigenmatrix.
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Acknowledgements
We thank Ferdinand Ihringer for his feedback regarding this paper. We also thank the two anonymous reviewers whose comments helped improve and clarify this manuscript. The research of S. M. Cioabă was supported by the Grants NSF DMS-1600768, CIF-1815922, and a JSPS Invitational Fellowship for Research in Japan (Short-term S19016).
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Cioabă, S.M., Gupta, H. On the Eigenvalues of Grassmann Graphs, Bilinear Forms Graphs and Hermitian Forms Graphs. Graphs and Combinatorics 38, 30 (2022). https://doi.org/10.1007/s00373-021-02445-z
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DOI: https://doi.org/10.1007/s00373-021-02445-z