Periodic orbit-closure conjecture for exact-cluster tilings

About 13 years old · traced to

Let F⊆Z2F\subseteq\mathbb{Z}^2 be an exact cluster with full affine span, and let TT be an FF-tiling. The orbit closure of TT is

Z2⋅T‾=cl⁡{v⋅T:v∈Z2}.\overline{\mathbb{Z}^2\cdot T}=\operatorname{cl}\{v\cdot T:v\in\mathbb{Z}^2\}.

A tiling is 11-periodic if it has a nonzero period in Z2\mathbb{Z}^2.

Periodic orbit-closure conjecture. The orbit closure

Z2⋅T‾\overline{\mathbb{Z}^2\cdot T}

contains a 11-periodic FF-tiling.

This conjecture would extend the expected link between low pattern complexity and periodicity to tilings by possibly non-convex windows. The paper states that its counterexample refutes this conjecture, so it is disproved.

References

Primary source

Abhishek Khetan, “A Counterexample to Nivat's Conjecture for a Non-Convex Window of Full Affine Span”, arXiv:2607.09830 (2026).

Additional references

3 papers in this index state this conjecture (2013–2026). The statement above is taken from the most recent of them; the others are arXiv:2507.12654, arXiv:1312.0386.

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.