Asymptotic Erdős–Gallai theorem for hypergraph matchings

Determine whether the inequality in the trivial lower bound for the extremal number of tilings by the complete $r$-uniform hypergraph $K_{1,\\ldots,1}^{r}$ holds with equality for all $r\ge 3$, thereby extending the Erdős–Gallai Theorem from graphs to higher-uniformity hypergraphs.

Background

The paper studies extremal numbers of the form ex(n,(k+1)F)\mathrm{ex}(n,(k+1)F), where the host rr-graph is required to have matching number below k+1k+1 with respect to a fixed rr-graph FF. For complete rr-partite rr-graphs, the authors introduce a family of natural constructions Gn,i,β(s1,,sr)G_{n,i,\beta}(s_1,\ldots,s_r) that provide lower bounds for these extremal numbers.

When F=K1,,1rF=K_{1,\ldots,1}^{r}, the relevant construction has two competing extremal forms, corresponding to i=1i=1 and i=ri=r. The Erdős–Gallai Theorem proves equality in the analogous lower bound for ordinary graphs (r=2r=2), while the higher-uniformity extension is identified as a major unresolved problem.

References

Extending the Erdős--Gallai Theorem to $r \ge 3$ is a major open problem in Extremal Combinatorics.

Tiling $H$ in dense graphs  (2501.11450 - Chen et al., 20 Jan 2025) in Section 1, Introduction