2210.14733
AN ASYMPTOTIC FOR SUMS OF LYAPUNOV EXPONENTS IN FAMILIES
Patrick Ingram, David Jaramillo-Martinez, Jorge Mello
correctmedium confidence
- Category
- math.DS
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The uploaded paper proves exactly the asymptotic L(f_t) = L(f_η) log|t^{-1}| + O((log|t^{-1}|)^{1−ε_N}) with ε_N = 1/(3N+4) for meromorphic families over P^1_K, by (i) deriving effective bounds for norms of homogeneous forms in t via an effective Nullstellensatz and height/Mahler–Gauss comparisons, (ii) expressing L(f_t) through the escape-rate/Green functional for the Jacobian via pushforwards, and (iii) optimizing over the iterate length to obtain the power saving; the leading coefficient is identified with the non-Archimedean Lyapunov sum using Favre’s theorem (Theorem 2 and its proof, together with Lemmas 6, 8, 9 and the final comparison with Favre’s asymptotic) . The candidate solution follows the same blueprint: lift to F_t, reduce L(f_t) to growth of pushforwards of divisors/hyperplanes using Ingram’s formula, obtain power-saving bounds via Jelonek’s effective Nullstellensatz plus height/Mahler estimates, and identify the leading coefficient by Favre. The steps, hypotheses, exponent, and identification of constants align closely with the paper’s sections “Effective estimates on norms of homogeneous forms,” “Lifts and pushforwards of divisors,” and “Variation of the escape rate” . Hence both are correct and use substantially the same proof.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} specialist/solid \textbf{Justification:} The paper delivers a concrete, effective strengthening of Favre’s degeneration asymptotic by exhibiting a power-saving error with an explicit exponent depending only on N. The proof is conceptually clean—effective Nullstellensatz and height/Mahler tools feed into a pushforward/escape-rate formalism—and should be of practical use in complex and arithmetic dynamics. A few clarifications regarding constants, the s↔1/s change of variables, and the identification of the leading coefficient would improve accessibility.