Time: 9h30, Thursday, December 17, 2020.

Location: Room 612, Building A6.

Abstract: M.A. Henning and A. Yeo conjectured in [{it SIAM J. Discrete Math.}, 26 (2012), 687 -- 694] that a bipartite digraph of minimum out-degree at least 3 contains two vertex disjoint directed cycles of different lengths. In this paper, we disprove this conjecture. Further, we classify strong tournaments and strong bipartite tournaments of minimum out-degree 3 without two vertex disjoint directed cycles of different lengths.