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2202.03456

Distal Systems in Topological Dynamics and Ergodic Theory

Nikolai Edeko, Henrik Kreidler

correctmedium confidence
Category
math.DS
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves that every ergodic distal system admits a minimal distal topological model (metrizable in the separable case) by climbing the Furstenberg–Zimmer distal tower, choosing at each successor stage a canonical pseudoisometric topological model for the relatively discrete-spectrum extension (Theorem 3.6), and taking projective limits at limit ordinals; minimality is deduced from the existence of a fully supported ergodic measure (Lemma 4.10), yielding Theorem 4.9 . The candidate solution mirrors this architecture: build along the distal tower via compact (isometric) extensions, then pass to the inverse limit; ensure full support and metrizable models in the separable case. Minor issues in the model include an overclaim that Haar-fiber measures yield ergodicity without additional hypotheses and conflating pseudoisometric with isometric in the non-metrizable context. These do not affect the overall existence proof, which aligns closely with the paper’s method.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The paper gives a robust, conceptually unified proof that every ergodic distal system has a canonical minimal distal topological model, extending known results beyond the separable setting. The operator-theoretic perspective and the canonical modeling of relatively discrete-spectrum extensions make the argument clean and flexible. Some minor expository expansions (projective-limit ergodicity, explicit role of metrizability in isometric upgrades) would enhance readability.