Wichmann's Conjecture on Optimal Sparse Rulers
TheoremDB P8790 · Candidate awaiting source review
Inferred from the community field; finer classification has not been reviewed.
Problem statement
A sparse ruler is described by a finite sequence of positive integers called segment lengths or gaps. Its marks are the partial sums where , and is the length of the ruler. A distance is measurable if for some marks .
A sparse ruler is complete if every distance is measurable. A complete ruler is minimal if no complete ruler of the same length has fewer segments. A complete ruler is maximal if no complete ruler with the same number of segments has greater length. A ruler is optimal if it is both minimal and maximal.
For natural numbers and , the Wichmann ruler is the sparse ruler with segment-length sequence
where denotes consecutive segments of length . This ruler has segments and length .
Prove that if is an optimal sparse ruler with more than segments, then there exist natural numbers and such that equals or the reverse of .
Lean 4
Formal statement
Lean 4theorem wichmann_conjecture {g : List ℕ} (hopt : IsOptimal g) (hseg : 13 < g.length) :
∃ r s : ℕ, g = wichmannGaps r s ∨ g = (wichmannGaps r s).reverseOn-site verification needs an executable Lean target. None is attached yet.
A source attachment or link is not a verified proof. The statement’s correspondence with the original question needs human review.
Proofs & verification
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Progress & source assessment
Source-reported assessment, retrieved 8 September 2026. Frontier Science has not independently reviewed this status.
Open. No signed Lean verification is attached to this problem or its selected resolution.
This record is in the source backlog; its novelty and unresolved status have not passed source review.
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