A problem of Erdős and Hajnal on paths with equal-degree endpoints

Fuente: arXiv
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Main Authors: Chen, Kaizhe, Ma, Jie
Format: Preprint
Published: 2025
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author Chen, Kaizhe
Ma, Jie
author_facet Chen, Kaizhe
Ma, Jie
contents We address a problem posed by Erdős and Hajnal in 1991, proving that for all $n \geq 600$, every $(2n+1)$-vertex graph with at least $n^2 + n + 1$ edges contains two vertices of equal degree connected by a path of length three. The complete bipartite graph $K_{n,n+1}$ demonstrates that this edge bound is sharp. We further establish an analogous result for graphs with even order and investigate several related extremal problems.
format Preprint
id arxiv_https___arxiv_org_abs_2503_19569
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A problem of Erdős and Hajnal on paths with equal-degree endpoints
Chen, Kaizhe
Ma, Jie
Combinatorics
We address a problem posed by Erdős and Hajnal in 1991, proving that for all $n \geq 600$, every $(2n+1)$-vertex graph with at least $n^2 + n + 1$ edges contains two vertices of equal degree connected by a path of length three. The complete bipartite graph $K_{n,n+1}$ demonstrates that this edge bound is sharp. We further establish an analogous result for graphs with even order and investigate several related extremal problems.
title A problem of Erdős and Hajnal on paths with equal-degree endpoints
topic Combinatorics
url https://arxiv.org/abs/2503.19569