Mészáros–Rónyai conjecture on deleting a member of an s-extremal family

From papers

For a family F2[n]\mathcal{F}\subseteq 2^{[n]}, let tr(F)\operatorname{tr}(\mathcal{F}) be its trace family. The family is s-extremal when

tr(F)=F.|\operatorname{tr}(\mathcal{F})|=|\mathcal{F}|.

Mészáros–Rónyai conjecture. For every nonempty s-extremal family F2[n]\mathcal{F}\subseteq 2^{[n]}, there exists F0FF_0\in\mathcal{F} such that F{F0}\mathcal{F}\setminus\{F_0\} is still s-extremal.

The conjecture is known for hereditary families and for all families with VC dimension at most 22; it remains open in general.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Mingze Li, Jie Ma and Mingyuan Rong, “Recent advances in arrow relations and traces of sets”, arXiv:2507.23375 (2025).

Solutions 0

No solutions have been posted yet.