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2508.00266

Finite index theorems for iterated Galois groups of preperiodic points for unicritical polynomials

Minsik Han, Thomas J. Tucker

correctmedium confidence
Category
Not specified
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:57 AM

Audit review

The uploaded paper proves that for f(x)=x^q+c with q a prime power, 0 not preperiodic, and β strictly preperiodic, the index [G∞:G∞(β)] is finite (Theorem 1.2) and reduces this to certifying that, for all large n, Gal(Kn(β)/Kn−1(β)) attains the full Kummer kernel (Cq)^{q^{n−1}} (Proposition 2.1) by producing primes satisfying Conditions R/U and a multi-branch independence criterion (Propositions 4.7 and 4.9, combined with Proposition 5.1 and Theorem 5.3) . By contrast, the candidate solution makes a crucial incorrect reduction: it replaces β by a periodic α=f^m(β) and claims the towers agree from level m onward, which is false in general, and it does not supply the paper’s precise Conditions R/U or eventual stability/irreducibility inputs. It also attributes the key prime construction to a different source (squarefree portrait primes) than the paper’s actual Proposition 3.1 mechanism. Thus the paper’s argument is correct and complete for its claims, while the model’s proof outline has a fundamental flaw and missing hypotheses.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The paper gives a clean, unconditional finite-index theorem for arboreal representations of x\^q+c with strictly preperiodic basepoints, using eventual stability, a carefully crafted diophantine prime-construction, and Kummer-theoretic ramification control. The logical flow is sound and the results are significant within arithmetic dynamics. Minor revisions could improve exposition (explicit dependence of constants, a schematic of the argument, and small clarifications in the multi-branch independence step).