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2010.11094

Structure of Julia Sets for Post-Critically Finite Endomorphisms on P2

Zhuchao Ji

correcthigh confidence
Category
Not specified
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:55 AM

Audit review

Ji’s paper proves the two desired statements for PCF endomorphisms on P^2 (Theorem 1.1) and does so by a two-step argument: (i) every x in J1 \ J2 admits a Fatou disk (Theorem 4.5), and (ii) any point of J1 lying on a Fatou disk must be in a basin of a critical component cycle or in the stable manifold of a sporadic super‑saddle cycle (Theorem 4.8). These steps rely on Ueda’s covering/normal-family machinery (Corollary 2.6 and Lemma 2.7) and an exclusion of Siegel varieties, together with standard facts about attracting critical components and basins (Section 1.2) and the location/type of periodic points. The paper also notes (as a corollary) laminarity of T in J1 \ J2, originally due to de Thélin. By contrast, the model’s proof substantially overstates what laminarity yields: it asserts a Fatou disk through every point of J1 \ J2 from laminarity of T, while laminarity only guarantees plaques for σ_T-almost every point (see the background paragraph immediately before Corollary 1.5). It also sketches a Weierstrass-based global contraction for periodic critical components without invoking the precise Fornæss–Sibony trapping-region estimate, invokes a nonstandard graph-transform/stable-manifold argument at a super-saddle with a zero eigenvalue, and relies on an unsubstantiated exclusion of invariant curves disjoint from PC(f) to conclude that limits of fn|_D must be constant. The paper’s argument is complete and correct; the model’s proof contains gaps and overclaims. See Theorem 1.1, Theorem 4.5, Theorem 4.8, the laminarity background and corollary, and the facts on attracting critical components cited in Section 1.2.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The paper establishes a clear structural picture of J1 \ J2 for PCF maps on P\^2 and rules out Fatou disks in J2 away from super-saddle stable manifolds. The approach is methodical, leveraging Ueda’s machinery to produce and classify Fatou disks, and it yields meaningful corollaries (laminarity of T, expanding/Axiom A characterizations). Minor clarifications would further ease reading, but the results and proofs are solid and significant.