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Proof a conjecture on connectivity keeping odd paths in k-connected bipartite graphs

Qing Yang, Yingzhi Tian

Abstract

Luo, Tian and Wu (2022) conjectured that for any tree $T$ with bipartition $X$ and $Y$, every $k$-connected bipartite graph $G$ with minimum degree at least $k+t$, where $t=$max$\{|X|,|Y|\}$, contains a tree $T'\cong T$ such that $G-V(T')$ is still $k$-connected. Note that $t=\lceil\frac{m}{2}\rceil$ when the tree $T$ is the path with order $m$. In this paper, we proved that every $k$-connected bipartite graph $G$ with minimum degree at least $k+ \lceil\frac{m+1}{2}\rceil$ contains a path $P$ of order $m$ such that $G-V(P)$ remains $k$-connected. This shows that the conjecture is true for paths with odd order. And for paths with even order, the minimum degree bound in this paper is the bound in the conjecture plus one.

Proof a conjecture on connectivity keeping odd paths in k-connected bipartite graphs

Abstract

Luo, Tian and Wu (2022) conjectured that for any tree with bipartition and , every -connected bipartite graph with minimum degree at least , where max, contains a tree such that is still -connected. Note that when the tree is the path with order . In this paper, we proved that every -connected bipartite graph with minimum degree at least contains a path of order such that remains -connected. This shows that the conjecture is true for paths with odd order. And for paths with even order, the minimum degree bound in this paper is the bound in the conjecture plus one.
Paper Structure (4 sections, 10 theorems, 5 equations)

This paper contains 4 sections, 10 theorems, 5 equations.

Key Result

Theorem 1.1

(Chartrand) Every $k$-connected graph $G$ with minimum degree at least $\lfloor\frac{3k}{2}\rfloor$ contains a vertex $v$ such that $\kappa (G-v)\geq k$.

Theorems & Definitions (13)

  • Theorem 1.1
  • Theorem 1.2
  • Conjecture 1
  • Theorem 1.3
  • Conjecture 2
  • Theorem 1.4
  • Conjecture 3
  • Lemma 2.1
  • Lemma 2.2
  • Lemma 2.3
  • ...and 3 more