Chvátal's conjecture on subset-closed families

Let F{\cal F} be a family of sets. It is subset-closed if every subset of every member of F{\cal F} also belongs to F{\cal F}. Recall that F{\cal F} is EKR{\sf EKR} when some star Fx{\cal F}_x has size at least that of every intersecting subfamily HF{\cal H}\subseteq{\cal F}.

Chvátal's conjecture. Every subset-closed family of sets is EKR{\sf EKR}.

This conjecture asks for an Erdős–Ko–Rado-type extremal theorem for arbitrary subset-closed families. Its status is not specified in the source.

Sources & referencesView supporting material

Primary source

Neal Bushaw, James Danielsson and Glenn Hurlbert, “Erdős-Ko-Rado Theorems for Paths in Graphs”, arXiv:2504.05406 (2026).

Additional references

9 papers in this index state this conjecture (2011–2025). The statement above is taken from the most recent of them; the others are arXiv:2402.03150, arXiv:2201.03865, arXiv:1912.11641, arXiv:1809.01572, arXiv:1710.02518, arXiv:1511.08245, arXiv:1106.6144, arXiv:1103.3858.

Progress summary

Never refreshed

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

Solutions 0

No solutions have been posted yet.