Hojin Chu

collaborators

4 papers

math.CO2026

Existence of cycles of length divisible by 3 or 4

Ilkyoo Choi, Hojin Chu, Ringi Kim +1

Dean conjectured that for each integer $k \geq 3$ , every graph with minimum degree at least $k$ has a cycle whose length is divisible by $k$ ; this conjecture is known to be true for…

math.CO2024

Competition-common enemy graphs of degree-bounded digraphs

Myungho Choi, Hojin Chu, Suh-Ryung Kim

The competition-common enemy graph (CCE graph) of a digraph $D$ is the graph with the vertex set $V (D)$ and an edge $uv$ if and only if $u$ and $v$ have a common predator and a com…

math.CO2024

Digraphs in which every $t$ vertices share exactly $λ$ out-neighbors and exactly $λ$ in-neighbors

Hojin Chu, Suh-Ryung Kim

In this paper, we introduce the notion of two-way $(t, λ)$ -liking digraphs as a way to extend the results for generalized friendship graphs. A two-way $(t, λ)$ -liking digraph is a di…

math.CO2024

Digraphs in which every $t$ vertices have exactly $λ$ common out-neighbors

Myungho Choi, Hojin Chu, Suh-Ryung Kim

We say that a digraph is a $(t, λ)$ -liking digraph if every $t$ vertices have exactly $λ$ common out-neighbors. In 1975, Plesník [Graphs with a homogeneity, 1975. {\it Glasnik Mathe…

Existence of cycles of length divisible by 3 or 4

Competition-common enemy graphs of degree-bounded digraphs

Digraphs in which every t vertices share exactly λ out-neighbors and exactly λ in-neighbors

Digraphs in which every t vertices have exactly λ common out-neighbors

Digraphs in which every $t$ vertices share exactly $λ$ out-neighbors and exactly $λ$ in-neighbors

Digraphs in which every $t$ vertices have exactly $λ$ common out-neighbors