Zhang–Lu matching extremal conjecture for 3-uniform hypergraphs

Let HH be a 3-graph of order nn, let σ2(H)\sigma_2(H) be the minimum of deg(u)+deg(v)\deg(u)+\deg(v) over adjacent vertices u,vu,v, and let Hn,s2H_{n,s}^2 be the corresponding extremal 3-graph. Zhang–Lu matching extremal conjecture. There exists n0Nn_0\in\mathbb{N} such that, for every 3-graph HH of order nn0n\ge n_0 without isolated vertices, if

σ2(H)>2((n12)(ns2))\sigma_2(H)>2\left(\binom{n-1}{2}-\binom{n-s}{2}\right)

and n3sn\ge3s, then HH contains no matching of size ss if and only if HH is a subgraph of Hn,s2H_{n,s}^2. This extends the stated extremal matching result for the relevant degree-sum threshold; the supplied source gives no resolution of the conjecture.

Sources & referencesView supporting material

Primary source

Yan Wang and Yi Zhang, “Vertex degree sums for perfect matchings in 3-uniform hypergraphs”, arXiv:2401.03713 (2024).

Additional references

2 papers in this index state this conjecture (2017–2024). The statement above is taken from the most recent of them; the others are arXiv:1710.04752.

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