3 papers
math.CO2026
The perfect divisibility and chromatic number of some odd hole-free graphs
Weihua He, Yueping Shi, Rong Wu +1
A hole is an induced cycle of length at least 4, and an odd hole is a hole of odd length. It is NP-hard to color the vertices of an odd hole-free graph. A graph is perfectly di…
math.CO2025
Path Extendable Tournaments
Zan-Bo Zhang, Weihua He, Hajo Broersma +1
A digraph is called \emph{path extendable} if for every nonhamiltonian (directed) path in , there exists another path with the same initial and terminal verti…
math.CO2025
Cycles of lengths 3 and n-1 in digraphs under a Bang-Jensen-Gutin-Li type conditon
Zan-Bo Zhang, Wenhao Wu, Weihua He
Bang-Jensen-Gutin-Li type conditions are the conditions for hamiltonicity of digraphs which impose degree restrictions on nonadjacent vertices which have a common in-neighbor or a…