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2106.11859

Functional analysis approach to the Collatz conjecture

Mikhail Neklyudov

wronghigh confidence
Category
math.DS
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper states Theorem 2.2 for the Hardy space H^2(B0(1))/X, but its hypercyclicity proof computes ||S^n z^k||^2 = π/(2^n k + 1) → 0, which is the Bergman norm decay, not Hardy (where ||z^m||_{H^2} = 1), so the key step S^n→0 fails on Hardy and the proof is invalid as written . The operator and its action T(z^n)=z^{T(n)} are correctly defined, and the right inverse Sg(z)=g(z^2) does satisfy T∘S=Id . However, the divergent-orbit case is asserted “similar” without details and, as stated, cannot use the same dense set argument in H^2. The candidate solution fixes the space to the unweighted Bergman space A^2(D) (where ||z^m||^2=1/(m+1)), for which S^n→0 on polynomials and the Hypercyclicity Criterion applies; that argument is correct and fully consistent with the paper’s intended coefficient computations.

Referee report (LaTeX)

\textbf{Recommendation:} major revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The paper presents an appealing operator-theoretic framing of Collatz dynamics and several illustrative results. However, the principal hypercyclicity theorem is stated on the Hardy space but proved using Bergman-space norms, so the argument is incorrect in the stated setting. With a corrected statement (to Bergman) and a complete treatment or retraction of the divergent-orbit case, the contribution would be solid.