Hamiltonicity conjecture for the face lattice of every polytope

About 23 years old · traced to

Let PP be a polytope of dimension d≥1d\geq 1. Its face lattice L(P)L(P) consists of all faces of PP, ordered by inclusion, and G(L(P))G(L(P)) is the cover graph of this lattice: its vertices are the faces of PP, with two faces adjacent when one is a subface of the other and their dimensions differ by 11.

Hamiltonicity conjecture. The graph G(L(P))G(L(P)) has a Hamiltonian cycle.

Such a cycle would give a Gray code listing of all faces of PP, in which consecutive faces differ by a single cover relation in the face lattice. The source presents this as a brave conjecture and notes that the question appears to be novel; the available context gives no resolution.

References

Primary source

Nastaran Behrooznia, Sofia Brenner, Arturo Merino, Torsten Mütze, Christian Rieck and Francesco Verciani, “Listing faces of polytopes”, arXiv:2412.02584 (2026).

Additional references

5 papers in this index state this conjecture (2003–2024). The statement above is taken from the most recent of them; the others are arXiv:2205.15228, arXiv:1611.06401, arXiv:1206.4846, arXiv:math/0303084.

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.