A sufficient condition for pre-Hamiltonian cycles in bipartite digraphs

Samvel Kh. Darbinyan, Iskandar A. Karapetyan

Let $D$ be a strongly connected balanced bipartite directed graph of order $2a\ge 10$ other than a directed cycle. Let $x,y$ be distinct vertices in $D$. $\{x,y\}$ dominates a ver…