2407.01514
О спектральных задачах Колмогорова и Рохлина в классе перемешивающих автоморфизмов
V. V. Ryzhikov
correctmedium confidence
- Category
- Not specified
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper proves Theorem 1 by an explicit Q_r–P_r averaging/Gram-matrix argument that places Tr f ⊗ f + f ⊗ Tr f in the cyclic subspace of f ⊗ f and yields simplicity of T ⊙ T, failure of the group property, and multiplicity 2 for T ⊗ T when r_j ∼ j^d with d < 1/5. The candidate solution’s core Step 1 is incorrect: polynomials in U ⊙ U acting on f ⊙ f produce only diagonal terms U^n f ⊙ U^n f and cannot approximate off-diagonal vectors f ⊙ U^ℓ f as claimed; moreover, the posited O(r_j^5/h_j) error and its attribution to the paper are unsupported. The model thus reaches the right conclusions for the wrong reasons.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} specialist/solid \textbf{Justification:} The note gives a concise and plausible argument establishing explicit staircase examples with r\_j ~ j\^d, d < 1/5, that fail the group property and realize multiplicity two for T ⊗ T. The strategy via Q\_r–P\_r averaging and Gram-matrix bounds is sound. Minor additions clarifying the key lemma and the J\_r counting would improve accessibility without changing the substance.