2408.00616
BUNCHING FOR RELATIVELY PINCHED METRICS
Yannick Guedes Bonthonneau
correctmedium confidence
- Category
- math.DS
- Journal tier
- Strong Field
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The uploaded paper proves that under relative negative a^2 pinching, the horospherical foliation is C^{2a−} by deriving an averaged (periodic-orbit) inequality for the Riccati eigenvalues and invoking Hasselblatt’s criterion (see the statement of Theorem 1 and its proof outline, together with Proposition 3 and Theorem 2) . In contrast, the candidate solution hinges on a pointwise comparison λ_min(t) ≥ a λ_max(t) for the unstable Riccati operator derived directly from relative pinching of curvature; the paper explicitly notes that such a pointwise upgrade from a^2 to a is generally false (cf. the GHK obstruction) and replaces it by control of time-averaged quantities along periodic orbits . Thus, although the candidate reaches the right exponent 2a, its core argument uses an invalid step, while the paper’s proof is correct.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} strong field \textbf{Justification:} The paper gives a sharp improvement for the regularity of horospherical foliations under relative pinching, moving from 2a\^2 to the optimal 2a. The method—via an integral inequality for periodic Riccati solutions and an ergodic reduction to periodic orbits—clarifies why pointwise strengthening fails while an averaged inequality suffices. The exposition is concise; small additions (clearer handling of eigenvalue crossings and references for the measure/closing reduction) would enhance accessibility.