Back to search
2111.07714

Elliptic fixed points with an invariant foliation: Some facts and more questions

Alain Chenciner, David Sauzin, Shanzhong Sun, Qiaoling Wei

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

Audit review

The paper proves an alternative for each family Fλ, Fλ,•,g, Fλ,f,•: either basic normalizations are always convergent or else normalizations are generically divergent; it then shows generic divergence in two of the families for every irrational ω and, in the third, generic divergence when ω is non‑Brjuno. By contrast, the candidate claims a sharp arithmetic dichotomy—Brjuno implies convergence for every map in each family, non‑Brjuno implies generic divergence—which flatly contradicts the paper’s Theorem 30(i) asserting generic divergence in Fλ and Fλ,•,g for all ω. The model also attributes an “always-convergent” branch to Brjuno without proof in the paper.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The manuscript establishes a clear dichotomy (always convergence or generic divergence) for special normalizations in circle-preserving planar germs, then instantiates it with concrete generic divergence results. The formal scheme is clean and the Baire-category argument is persuasive. Minor clarifications on the scope of the always-convergent branch would improve readability and prevent misinterpretations (e.g., linking it to Brjuno).