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2107.07262

QUADRATIC RATIONAL MAPS WITH INTEGER MULTIPLIERS

Valentin Huguin

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

Audit review

The paper proves that if a quadratic rational map f has all multipliers for cycles of periods up to 5 in the ring RD of an imaginary quadratic field, then f is conjugate to a power map, a Chebyshev map, or a Lattès map (Theorem 9) . The proof uses multiplier/dynatomic polynomials together with the holomorphic fixed-point identity 1/(1−λ1)+1/(1−λ2)+1/(1−λ3)=1, a reduction via moduli parameters (σ1,σ2), and a finite case analysis split into three lemmas: (i) no superattracting or multiple fixed point ⇒ power or Lattès (Lemma 28), achieved by enumerating fixed-point multipliers from RD and testing splitting of M3, M4, M5, with non-Lattès/non-power triples excluded by irreducibility/degree arguments over quadratic extensions ; (ii) with a superattracting fixed point, working in the polynomial normal form z↦z^2+c and using discriminants and splitting of M1, M3 (and checking M4) forces c∈{−2,0}, i.e., Chebyshev or power (Lemma 29) ; and (iii) multiple fixed points are excluded (Lemma 30) . The splitting criterion relating multipliers and multiplier polynomials is stated explicitly (Corollary 20) , and the dependence of M_n on (σ1,σ2) is given (Proposition 23) . The candidate solution follows the same architecture: dynatomic/multiplier polynomial technology; Milnor–Silverman moduli; finite Diophantine analysis of fixed-point multipliers; and the same trichotomy. Minor discrepancies include: referring to the parameter as 0 or ±2 in the superattracting normal form (the paper finds c∈{−2,0} in z^2+c), and mentioning M2 where the paper uses M1 and M3; these do not change the classification. The model’s outline also correctly notes that quadratic Lattès multipliers lie in RD (Milnor) and uses the paper’s list of quadratic Lattès fixed-point multipliers as a recognition tool (Corollary 27) . Overall, the proofs are substantially the same and correct.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The result settles a natural and nontrivial classification in degree 2, dovetailing arithmetic constraints (multipliers in an imaginary quadratic order) with complex dynamics. The arguments are standard but deftly combined with explicit finite checks. The paper is clear and carefully written; a few presentation improvements would enhance readability without changing substance.