Hojin Chu

activity

20242026

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8 papers · 1 filter

math.CO2026

Connectivity keeping paths in digraphs

Hojin Chu, Boram Park, Homoon Ryu

Mader conjectured that every $k$ -strong digraph $D$ with minimum semidegree $δ^{0} (D) \geq 2 k + m - 1$ contains a dipath $P$ of order $m$ such that $D - V (P)$ remains $k$ -strong. For $k = 1$ ,…

math.CO2026

A sharp extension of Halin's removable-edge theorem to matchings

Hojin Chu

A subgraph $H$ of a $k$ -connected graph $G$ is called \emph{ $k$ -removable} if $G - E (H)$ remains $k$ -connected. Halin proved that every $k$ -connected graph $G$ with $δ (G) \geq k + 1$ has…

math.CO2026

Minimum degree conditions for removable matchings in $k$ -connected graphs

Hojin Chu, Ringi Kim, Boram Park

In 1969, Halin proved that every $k$ -connected graph $G$ with minimum degree at least $k + 1$ contains an edge $e$ such that $G - e$ is $k$ -connected. As an edge is a matching of size…

math.CO2026

On 2-connected graphs without cycles of length 1 modulo 3

Yandong Bai, Hojin Chu, Binlong Li +2

Burr and ErdÅs conjectured in 1976 that for all integers $k > ℓ \geq 0$ such that $k Z + ℓ$ contains an even integer, every $n$ -vertex graph without cycles of length $\el…

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

On $2$ -connected graphs avoiding cycles of length $0$ modulo $4$

Hojin Chu, Boram Park, Homoon Ryu

For two integers $k$ and $ℓ$ , an $(ℓ mod k)$ -cycle means a cycle of length $m$ such that $m \equiv ℓ (mod k)$ . In 1977, BollobÃ¡s proved a conjecture of Burr and Er…

Connectivity keeping paths in digraphs

A sharp extension of Halin's removable-edge theorem to matchings

Minimum degree conditions for removable matchings in k-connected graphs

On 2-connected graphs without cycles of length 1 modulo 3

Connectivity keeping trees in triangle-free graphs

On 2-connected graphs avoiding cycles of length 0 modulo 4

Minimum degree conditions for removable matchings in $k$ -connected graphs

On $2$ -connected graphs avoiding cycles of length $0$ modulo $4$