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2106.15712

INVARIANT MEASURES FOR RANDOM EXPANDING ON AVERAGE SAUSSOL MAPS

Fawwaz Batayneh, Cecilia González-Tokman

correctmedium confidence
Category
Not specified
Journal tier
Specialist/Solid
Processed
Sep 28, 2025, 12:56 AM

Audit review

The paper proves, via a Lasota–Yorke inequality on the bounded-oscillation space V_α, that Cesàro averages H^s_ω of iterates h^k_ω are relatively compact and converge in L^1 to a random invariant density h_ω (Theorem 5.2), using the hybrid LY bound (4.9) and the explicit growth control Θ(ω) from (5.5) . It then shows r ≤ dim Y1(ω) for the number of ergodic skew-product ACIPs (Corollary 5.4) via an Oseledets splitting , and derives the packing bound r ≤ m(C)/(γ_N · ess inf_ω Θ(ω)^{N/α}) (Theorem 6.1), relying on the ‘positivity on a ball’ lemma for V_α (Lemma 2.5) . The candidate solution follows the same structure: (1) the same LY-driven uniform bounds and compactness argument (Kolmogorov–Riesz in place of [19, Lemma A.1]), (2) the same Oseledets-top-subspace argument and linear independence of ergodic densities, and (3) the same ball-positivity plus packing estimate producing the stated upper bound. Minor presentation differences include an explicit normalization remark for h_ω (the paper implicitly treats 1 as a seed while defining densities of mass 1) and different references for quasi-compactness; neither affects correctness. Overall, the proofs are essentially the same and correct.

Referee report (LaTeX)

\textbf{Recommendation:} minor revisions

\textbf{Journal Tier:} specialist/solid

\textbf{Justification:}

The manuscript develops a random Lasota–Yorke framework on the bounded-oscillation space V\_α and applies it to establish existence of random invariant densities, quasi-compactness, and an explicit bound on the number of ergodic skew-product ACIPs. The method is technically solid, aligns with the transfer-operator and Oseledets literature, and the results are of clear interest to specialists in random dynamical systems. Minor clarifications would further improve readability (normalization, measurability remarks, and a brief recap of the positivity-on-balls lemma).