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2107.03631

Reconstructing a Minimal Topological Dynamical System from a Set of Return Times

Kamil Bulinski, Alexander Fish

correctmedium confidence
Category
Not specified
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper’s Theorem 1.4 is proved by building the product orbit-closure Θ ⊂ X×K under S(x,k)=(Tx,k+α), defining H={h∈K:(x0,h)∈Θ}, showing H is a closed subgroup, then proving H⊂StabK(U′); since StabK(U′)={0}, H is trivial, so the X-projection is injective and yields the desired factor map φ with φ(Tx)=φ(x)+α and φ(x0)=0. This argument is complete and correct in the paper’s Section 2 (see the statement and set-up of Theorem 1.4 and its proof via Θ and H ⊂ StabK(U′) in the text) . By contrast, the candidate solution tries to force a unique K-fiber using an intersection of two syndetic sets; but two syndetic sets need not intersect (e.g., evens vs. odds), so the key step is invalid. The paper’s subgroup–stabilizer approach avoids this pitfall, while the model’s proof relies on a false combinatorial assumption, rendering it incorrect.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The work establishes a compelling reconstruction principle from return-time data to Kronecker (and related) structure, using a robust orbit-closure and stabilizer argument. The main theorems are clearly stated and proved with appropriate care. Minor expository enhancements—especially emphasizing why the stabilizer method is necessary and guarding against common pitfalls with syndetic sets—would improve readability for a broader dynamics audience.