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Erdős-Gallai-Tuza Conjecture


The Erdős-Gallai-Tuza conjecture asserts that, for every simple graph G on n vertices,

 alpha_1(G)+tau_1(G)<=(n^2)/4,

where alpha_1(G) is the largest size of a set of edges containing at most one graph edge from each triangle, and tau_1(G) is the smallest number of edges meeting every triangle (Erdős et al. 1996).

Norin and Sun (2016) proved the stronger inequality obtained by replacing tau_1(G) with the minimum number of edges whose deletion makes G bipartite. Such a deletion destroys every triangle, so the stronger bound implies the conjecture.

This is problem 621 in the Erdős problems collection (Bloom 2026).


See also

Bipartite Graph, Erdős Problems, Triangle-Free Graph

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References

Bloom, T. F. "Erdős Problem 621." Accessed Oct. 26, 2026. https://www.erdosproblems.com/621.Erdős, P.; Gallai, T.; and Tuza, Z. "Covering and Independence in Triangle Structures." Disc. Math. 150, 89-101, 1996. https://doi.org/10.1016/0012-365X(95)00178-Y.Norin, S. and Sun, Y. R. "Triangle-Independent Sets vs. Cuts." 13 Feb 2016. https://arxiv.org/abs/1602.04370.

Cite this as:

Weisstein, Eric W. "Erdős-Gallai-Tuza Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Erdos-Gallai-TuzaConjecture.html

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