4 papers
Natural graph spectra
Ziqing Xiang
In 2003, van Dam and Haemers posed a fundamental question in spectral graph theory: does there exist a ``sensible'' matrix whose spectrum determines a random graph up to isomorphis…
The non-existence of some Moore polygons and spectral Moore bounds
Sebastian M. CioabÄ, Vishal Gupta, Hiroshi Nozaki +1
In this paper, we study the maximum order of a connected -regular graph whose second largest eigenvalue is at most . From Alon-Boppana and Serre, we know that $v(k…
On Lattice Tilings of Asymmetric Limited-Magnitude Balls $\cB(n,2,m,m-1)$
Zhihao Guan, Hengjia Wei, Ziqing Xiang
Limited-magnitude errors modify a transmitted integer vector in at most entries, where each entry can increase by at most $\kp$ or decrease by at most $\km$. This channel model…
Codes with symmetric distances
Gábor Hegedüs, Sho Suda, Ziqing Xiang
For a code in a space with maximal distance , we say that has symmetric distances if its distance set is symmetric with respect to . In this paper, we prov…