Back to search
2108.02454

On Cartwright-Littlewood Fixed Point Theorem

Przemysław Kucharski

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

Audit review

The paper’s Theorem 1.5 states exactly the target claim and supplies two independent, detailed proofs: (i) a Hamilton–Brouwer-style extension argument using nested disks and the plane translation theorem (First proof of Theorem 1.5) , and (ii) a second proof via Ostrovski’s result plus the construction of a descending sequence of closed topological disks whose intersection is the component C (Lemma 2.5 and Second proof of Theorem 1.5) . The statement and context of the result are set out clearly in the introduction and abstract . By contrast, the model’s solution hinges on Step 1, which asserts the existence of a connected component D of Y = ⋂_{n≥0} h^{-n}(X) that contains the entire forward orbit O+(c). This is not justified: O+(c) need not lie in a single component of Y, so the subsequent use of nested inclusions D ⊇ h(D) ⊇ h^2(D) … and the construction of F = ⋂ h^n(D) are not validated. The remaining steps (fill-in lemma, nonseparating conclusions, Cartwright–Littlewood) would be fine if Step 1 were correct, but as stated the argument has a fatal gap.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The manuscript establishes a clear generalization of the Cartwright–Littlewood theorem and answers a published question. The two proofs are well-chosen and complementary. The exposition is largely crisp, though a handful of transitions and constructions would benefit from minor clarifications and illustrative figures.