On Hadamard diagonalizable graphs

@article{Barik2011OnHD,
  title={On Hadamard diagonalizable graphs},
  author={Sasmita Barik and Shaun M. Fallat and Steve Kirkland},
  journal={Linear Algebra and its Applications},
  year={2011},
  volume={435},
  pages={1885-1902}
}
Of interest here is a characterization of the undirected graphs G such that the Laplacian matrix associated with G can be diagonalized by some Hadamard matrix. Many interesting and fundamental properties are presented for such graphs along with a partial characterization of the cographs that have this property. 
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