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2508.05713

Dynamical systems with bounded condition and C∗-algebras

Takehiko Mori

correctmedium confidence
Category
math.DS
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:57 AM

Audit review

The paper proves that under the bounded condition there is an injective, order-preserving map K ↦ H_K from f-invariant sets to reducing subspaces, and that under the totally uniqueness condition this map is bijective (Theorems 3.6 and 3.7). Its surjectivity proof uses the projections P_m = T_{i_1}^*⋯T_{i_m}^* T_{i_m}⋯T_{i_1} built from the itinerary of x, showing P_m a → ⟨a,e_x⟩ e_x and then defining K = {x : ⟨a, e_x⟩ ≠ 0 for some a ∈ M} to get M = H_K . The candidate solution proves the same classification but via a different operator-theoretic route: it identifies the same P_m as cylinder projections E_w = T_w^* T_w, proves E_{w_ℓ} ↓ p_x strongly using total uniqueness, and then uses commutation P_M E_{w_ℓ} = E_{w_ℓ} P_M and strong limits to diagonalize P_M and conclude M = H_K. Both arguments rely on the same hypotheses (bounded condition to define the Ti, total uniqueness for the rank-one/point mass limit) and reach the same conclusion; the model’s proof is a clean SOT-limiting variant of the paper’s constructive argument. The definitions of the setting and of the totally uniqueness condition match the paper’s setup .

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The main results on the injection and bijection between f-invariant subsets and reducing subspaces are correct and clearly motivated. The proof of surjectivity under total uniqueness is solid; a few expository enhancements would improve readability, especially connecting the projection P\_m with cylinder sets and making the invariance check for K explicit. The contribution is specialized but useful for the operator-algebraic study of bounded dynamical systems.