2507.04215
Rational maps with constant Thurston pullback mapping
Guizhen Cui, Yiran Wang
correcthigh confidence
- Category
- Not specified
- Journal tier
- Strong Field
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper’s main theorem explicitly states and proves that every non‑trivial regular or mixing CTP polynomial satisfies McMullen’s condition (Theorem 2.1) . The proof proceeds by: (i) using the topological characterization of CTP maps (Theorem A) to deduce that f(E) is a single point and #(A\E) ≤ 2 (Lemma 3.4) ; (ii) treating the Belyi case (#V_f = 3) via monodromy/branched-tree arguments to obtain Stab(a) = Stab∗(E) (Lemma 5.4), and then applying the “power factor” lemma to conclude McMullen’s condition (Lemma 5.5) ; and (iii) reducing the general case to the Belyi case by a pinching construction that produces a non‑trivial CTP Belyi polynomial (Lemma 6.1) and a monodromy injection preserving stabilizers (Lemma 6.2), together with an alternate pinching argument yielding Stab(a) = Stab∗(E) for the original map (Lemma 6.3) . In contrast, the model’s argument hinges on an unsubstantiated differential rank bound that would force |F| = |f(E) ∪ V_f| ≤ 3 and on a claim that degree‑2 constant pullbacks are impossible. The former contradicts the paper’s framework (f may have many critical values even when it factors through a Belyi map via McMullen’s condition), and the latter is false in light of McMullen’s construction, which gives degree‑2 polynomial examples by composing g with z^2 and appropriate markings (see the McMullen example and its use throughout the paper) . Consequently, the model’s proof is unsound, while the paper’s proof is coherent and complete.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} strong field \textbf{Justification:} The manuscript proves a clear classification: non-trivial regular or mixing CTP polynomials satisfy McMullen’s condition. The method—topological characterization, monodromy on branched trees, and a carefully constructed pinching reduction to the Belyi case—is logically coherent and avoids delicate analytic estimates. The exposition is overall readable, though some technical constructions could be expanded with additional detail and figures to aid the reader.