4 papers
Existence of cycles of length divisible by 3 or 4
Ilkyoo Choi, Hojin Chu, Ringi Kim +1
Dean conjectured that for each integer , every graph with minimum degree at least has a cycle whose length is divisible by ; this conjecture is known to be true for…
Digraphs in which every vertices have exactly common out-neighbors
Myungho Choi, Hojin Chu, Suh-Ryung Kim
We say that a digraph is a -liking digraph if every vertices have exactly common out-neighbors. In 1975, PlesnÃk [Graphs with a homogeneity, 1975. {\it Glasnik Ma…
Competition graphs of degree bounded digraphs
Hojin Chu, Suh-Ryung Kim
If each vertex of an acyclic digraph has indegree at most and outdegree at most , then it is called an digraph, which was introduced by Hefner~{\it et al.}~(1991). W…
A digraph version of the Friendship Theorem
Myungho Choi, Hojin Chu, Suh-Ryung Kim
The Friendship Theorem states that if in a party any pair of persons has precisely one common friend, then there is always a person who is everybody's friend and the theorem has be…