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2410.02614

Subexponential growth and C1 actions on one-manifolds

Sang-Hyun Kim, Nicolás Matte Bon, Mikael de la Salle, Michele Triestino

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

Audit review

The uploaded paper proves exactly the statement invoked by the model: Theorem 1.1 asserts that if G is countable with no finitely generated subgroup of exponential growth, then every action of G on a countable linearly (resp. circularly) ordered set is realized as the restriction of an action by C1 diffeomorphisms on an interval (resp. the circle), with a G-equivariant injective order-preserving map i: X → M. This is stated explicitly and proved via a more general Theorem 3.1 using a moderate ℓ1-function on X and an equivariant Yoccoz family construction, ensuring ρ(g) has derivative 1 at interval endpoints and extends C1 across accumulation points of i(X) (see Theorem 1.1 and Theorem 3.1 with properties (C1)–(C3) and the moderate ℓ1-function construction). The model’s solution simply cites this result and sketches the same construction ideas, so both are correct and essentially the same proof approach .

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} strong field

\textbf{Justification:}

This work gives a broadly applicable, conceptually simple realization theorem for C1 actions from order-preserving actions of groups of local subexponential growth. The proof is clean and leverages a new functional perspective (moderate ℓ1-functions) with standard but powerful smoothing tools (Yoccoz family). The result subsumes many known cases and clarifies the role of growth. Minor presentation enhancements would further improve accessibility.