2106.14001
The Veech Discrete 2-Circle Problem and Non-Integrable Flat Systems
J. Beck, W.W.L. Chen, Y. Yang
correctmedium confidenceCounterexample detected
- Category
- Not specified
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:56 AM
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Audit review
The paper proves Theorem 3.2 for flat finite polysquare-b-rational translation surfaces by constructing the interval exchange transformation of the α-flow, establishing ergodicity under the separation hypothesis for badly approximable α (Lemma 5.1), and then upgrading from almost-every starting point to every non-pathological starting point via a Furstenberg-style argument (Lemma 6.1), thereby obtaining uniform distribution of every half-infinite α-geodesic (Theorem 3.2) . The candidate solution incorrectly treats these b-rational surfaces as square-tiled/origami (hence lattice) surfaces and invokes Veech dichotomy; however, introducing b-rational gates fundamentally alters the structure (e.g., a 2-square-b surface with irrational b is not a polysquare surface and exhibits behavior that violates the classical uniform/periodic dichotomy) . The model also discards the separation hypothesis, which is essential to the paper’s ergodicity step and cannot be dropped in general . Moreover, the model’s projection-to-torus and “uniquely ergodic for all irrational α” claims contradict known counterexamples on 2-square-b surfaces for non–badly approximable α .
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions
\textbf{Journal Tier:} specialist/solid
\textbf{Justification:}
The manuscript extends uniform distribution results to a broader, non-integrable class of translation surfaces with b-rational gates under a natural separation condition and badly approximable slopes. The approach—via IETs, an ergodicity lemma exploiting bounded continued fractions, and an upgrade to all starting points—is coherent and technically sound in the presented outline. Some expository refinements would improve accessibility, especially around the separation lemma and illustrative examples.