Full upper-range saturation spectrum for Berge stars of size at least six

Determine the full upper range of the saturation spectrum for 3-uniform Berge-$K_{1,\ell}$ with every integer $\ell\ge 6$, without relying on the development of significant new tools.

Background

The paper completely determines the 3-uniform saturation spectrum of Berge-K1,5K_{1,5} when $5$ divides the number of vertices, and determines all but a constant number of values for Berge-K1,K_{1,\ell} when 5\ell\ge 5. The unresolved difficulty concerns the upper range for >5\ell>5, where the difference between the edge counts of the \ell-lantern and three copies of the complete 3-uniform hypergraph on \ell vertices grows with \ell.

For =5\ell=5, the authors can handle the finitely many possible deficits through seven cases. As \ell increases, this case analysis becomes infeasible; the authors specifically identify determining the complete upper range for all 6\ell\ge 6 as unresolved. They note that the case =6\ell=6 might be approachable with substantial effort, but that a general solution would require significant new tools.

References

While the l = 6 case may be resolvable with considerable effort, it is unclear how to determine the full upper range for all l ≥ 6 without the development of significant new tools.

The Saturation Spectrum of Berge Stars  (2502.17686 - Bushaw et al., 24 Feb 2025) in Section 6, Concluding remarks