In this paper we study the sequence (ci)0id for a distance-regular graph. In particular we show that if d 2j and cj = c > 1 then c2j > c holds. Using this we give improveme...
Abstract The wide diameter of a graph is an important parameter to measure faulttolerance of interconnection network. This paper proves that for any two vertices in de Bruijn undir...
The conditional diameter D of a digraph G measures how far apart a pair of vertex sets V1 and V2 can be in such a way that the minimum out-degree and the minimum in-degree of the ...
We prove results on the size of weakly and strongly separating set systems and matrices, and on cross-intersecting systems. As a consequence, we improve on a result of Katona and ...