C O ] 2 M ay 2 01 8 A spectral version of the Moore problem for bipartite regular graphs

@inproceedings{Cioaba2018CO,
  title={C O ] 2 M ay 2 01 8 A spectral version of the Moore problem for bipartite regular graphs},
  author={Sebastian M. Cioaba and Jack H. Koolen and Hiroshi Nozaki},
  year={2018}
}
Let b(k, θ) be the maximum order of a connected bipartite k-regular graph whose second largest eigenvalue is at most θ. In this paper, we obtain a general upper bound for b(k, θ) for any 0 ≤ θ < 2 √ k − 1. Our bound gives the exact value of b(k, θ) whenever there exists a bipartite distance-regular graph of degree k, second largest eigenvalue θ, diameter d… CONTINUE READING