Line digraph iterations and diameter vulnerability (Q1809740)

The authors have introduced an \((l_1,\dots ,l_c)-\)seed as a digraph satisfying two relatively simple conditions concerning existence of paths. Examples of seeds known as Kautz digraphs, de Bruijn digraphs, some bipartite digraphs and others are presented. The main theorem is based on the line digraph iteration and it has a lot of corollaries which improve already published or unpublished results (e.g., in \textit{D. Z. Du, D. F. Hsu}, and \textit{Y. D. Lyuu} [Discrete Math. 151, No. 1-3, 81-85 (1996; Zbl 0853.05043)]).