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arXiv · 1311.5332

On a Conjecture of Erdős, Gallai, and Tuza

Gregory J. Puleo
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Abstract

Erdős, Gallai, and Tuza posed the following problem: given an $n$-vertex graph $G$, let $τ_1(G)$ denote the smallest size of a set of edges whose deletion makes $G$ triangle-free, and let $α_1(G)$ denote the largest size of a set of edges containing at most one edge from each triangle of $G$. Is it always the case that $α_1(G) + τ_1(G) \leq n^2/4$? We have two main results. We first obtain the upper bound $α_1(G) + τ_1(G) \leq 5n^2/16$, as a partial result towards the Erdős--Gallai--Tuza conjecture. We also show that always $α_1(G) \leq n^2/2 - m$, where $m$ is the number of edges in $G$; this bound is sharp in several notable cases.

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Gregory J. Puleo. 2014-10-13. On a Conjecture of Erdős, Gallai, and Tuza. https://doi.org/10.1002/jgt.21828

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