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2211.08145

STRONG TOPOLOGICAL ROKHLIN PROPERTY, SHADOWING, AND SYMBOLIC DYNAMICS OF COUNTABLE GROUPS

Michal Doucha

correctmedium confidence
Category
Not specified
Journal tier
Strong Field
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper explicitly proves the equivalence: a countable group G has the strong topological Rokhlin property (STRP) if and only if for every n ≥ 2, projectively isolated subshifts are dense in SG(n) (Theorem 3.1) . The forward implication is established via a contrapositive Baire-category argument using continuity of the symbolic coding map Q(·,P) (Proposition 2.10) and Definition 2.22 of projectively isolated subshifts , while the reverse implication constructs a generic action as an inverse limit of projectively isolated subshifts satisfying a Fraïssé-style amalgamation scheme (Proposition 3.6) and shows its conjugacy class is dense Gδ (Propositions 3.8 and 3.9) . The candidate’s claim that the statement was “likely open as of cutoff” is therefore incorrect.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

The paper settles an explicit equivalence connecting generic actions on the Cantor space (STRP) with density of projectively isolated subshifts, using a robust mix of Baire-category arguments and inverse-limit constructions. The methods are sound and broadly applicable. Minor edits to guide the reader through the Gδ-orbit argument and to highlight the role of Definition 2.22 would further improve clarity.