Back to search
2110.09340

FIXED POINTS OF KOCH’S MAPS

Van Tu Le

correctmedium confidence
Category
Not specified
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves a clean trichotomy (Theorem A′) for eigenvalues μ of DG_{k,m} at fixed points, via a conjugate model F_{k,m} and a precise spectral analysis of the transpose L* on an invariant complement, culminating in Proposition 4.12: either μ=0 (k′=0), or μ is an eigenvalue of G_{k′,m′} at a fixed point outside the post‑critical set, or μ^m = λ^{m/m′} with μ^{m′}≠λ (all mutually exclusive) . The candidate solution reaches the same classification but relies on a flawed step: it assumes a one‑dimensional space of m′‑periodic particular solutions when μ^{m′}≠λ and “rescales” such a solution to force a closing condition. In fact, in that non‑resonant case the m′‑periodic particular solution is unique and cannot be rescaled, so the key equation used to deduce μ^m=λ^{m/m′} is not justified. The paper’s argument—based on the cyclic action of L* on a natural basis and a direct eigenvalue computation—does not suffer from this gap and is correct .

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The manuscript establishes a definitive classification of eigenvalues for Koch maps at fixed points and links them transparently to multipliers of associated unicritical polynomials. The alternative construction and the spectral decomposition are conceptually appealing and technically correct. Minor clarifications (e.g., guiding the reader through the invariant-subspace/annihilator picture and emphasizing uniqueness in the non-resonant inhomogeneous problem) would enhance readability.