2507.22713
Topological pressures of a factor map for nonautonomous iterated function systems
Yujun Ju, Lingbing Yang
correctmedium confidence
- Category
- math.DS
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:57 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper proves the NAIFS factor-inequality for topological pressure by a direct, fully topological argument using the fiber topological sup-entropy H(Φ;·) and equicontinuity-derived d*_n metrics. The main theorem states P(Φ, φ∘π) ≤ P(Ψ, φ) + sup_y H(Φ; π^{-1}(y)) and is proved in detail, including the definition of H(Φ;Y) and the final bounding of separated sums, culminating in the inequality (letting auxiliary parameters go to zero) . By contrast, the model’s solution hinges on (i) a variational principle for NAIFS pressure in exactly the form P = sup(h_μ + ∫φ dμ) over a suitable class of Φ-invariant measures on X and (ii) a nonautonomous Rokhlin-type entropy addition formula for factor maps. Neither ingredient appears in, nor is needed by, the paper; more importantly, the model does not justify these claims for the NAIFS framework defined here (pressure via word-averaged separated/spanning sums on X), where the appropriate “invariance” and relative entropy notions are delicate. Without rigorous, cited statements specialized to this NAIFS pressure, the model’s proof is not validated.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} specialist/solid \textbf{Justification:} The paper cleanly establishes a Bowen-type factor inequality for topological pressure in the NAIFS setting using a fully topological method tailored to the word-averaged NAIFS pressure and a fiber sup-entropy notion. The result refines a known inequality for free semigroup actions and extends nonautonomous analogues. The argument appears correct and is well-presented; a few local clarifications would enhance readability.