Shinya Fujita

collaborators

3 papers

math.CO2025

Connectivity keeping trees in triangle-free graphs

Hojin Chu, Shinya Fujita, Boram Park +1

In 2012, Mader conjectured that for any tree $T$ of order $m$ , every $k$ -connected graph $G$ with minimum degree at least $⌊ \frac{3 k}{2} ⌋ + m - 1$ contains a subtree $T'\c…

math.CO2025

Tight upper bounds on the hop domination number of triangle-free graphs

Shinya Fujita, Boram Park

For a graph $G$ , a subset $S$ of $V (G)$ is a {\it hop dominating set} of $G$ if every vertex not in $S$ has a $2$ -step neighbor in $S$ . The {\it hop domination number}, $γ_{h} (G)$ , o…

math.CO2012

Around a biclique cover conjecture

G. Chen, S. Fujita, A. Gyarfas +2

We address an old (1977) conjecture of a subset of the authors (a variant of Ryser's conjecture): in every r-coloring of the edges of a biclique [A,B] (complete bipartite graph), t…