arXiv:2410.18554v2

Tail behaviour of stationary densities for one-dimensional random diffeomorphisms

Jeroen S. W. Lamb, Guillermo Olicón-Méndez, Martin Rasmussen

math.PRmath.DS37H2037A5037C3060J0560G10

Abstract

We study the asymptotic behaviour of stationary densities of one-dimensional random diffeomorphisms, at the boundaries of their support, which correspond to deterministic fixed points of extremal diffeomorphisms. In particular, we show how this stationary density at a boundary depends on the underlying noise distribution, as well as the linearisation of the extremal diffeomorphism at the boundary point (in case the corresponding fixed point is hyperbolic), or the leading nonlinear term of the extremal diffeomorphism (in case the corresponding fixed point is not hyperbolic).

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Generated August 18, 2026
01Statements3 reported findingsCorrect

The hyperbolic and nonhyperbolic tail asymptotics for stationary densities of one-dimensional random diffeomorphisms are correct under the stated local normal-form and recurrence assumptions.

Theorems A and BCorrect

Stationary-density tails have the announced logarithmic scales

Pages 4–6 and Sections 3–5 · Theorems A–B · arXiv:2410.18554v2

In the hyperbolic case, inverse iterates grow exponentially at rate logλ\log\lambda, so the return index is logarithmic in distance and summing the renewal weights yields the log2\log^2 denominator. In the parabolic case, the embedded-flow normal form gives polynomial escape with exponent r1r-1; inversion and summation produce the displayed xr1logφ(x)/logxx^{r-1}\log\varphi(x)/\log x limit with the stated constant. The order of contact and density vanishing enter in the claimed combination k+1k+1.

Full paper, version 2
Theorem ACorrect

The hyperbolic boundary law has the stated quadratic-log exponent

Pages 5–6 · Theorem A and Section 4 · arXiv:2410.18554v2

The fixed point of the extremal map is hyperbolic, so successive inverse visits occur on a geometric spatial scale. The transition density vanishes to order kk at the extremal noise value, and multiplying the one-step weights through a logarithmic number of visits yields the stated quadratic-log asymptotic with coefficient determined by k+1k+1 and logλ\log \lambda.

Theorem BCorrect

The nonhyperbolic law reflects the correct contact order

Page 6 · Theorem B and Section 5 · arXiv:2410.18554v2

For contact order rr, the embedded local flow gives an escape time of order x1rx^{1-r}. Combining this with order-kk vanishing of the noise density gives the displayed normalization and constant. The theorem keeps the hyperbolic and parabolic regimes separate and its hypotheses supply the derivatives used in the normal form.

02Proofs3 reported findingsCorrect

The transfer-operator, inverse-hitting-time, and normal-form arguments are correct and complete.

Sections 3–5Correct and complete

Renewal sums and local dynamics are matched at the correct scale

Pages 9–23 · Sections 3–5 · arXiv:2410.18554v2

Distortion is uniform on the selected inverse branches, the entrance and exit errors are lower order after logarithmic normalization, and the stationary equation is iterated only where the local inverse is defined. The Sternberg and flow-embedding coordinates preserve the required asymptotic orders, and the two-sided bounds converge to the same constants.

Lemma 3.1 and Proposition 3.2Correct and complete

The stationary equation is reduced to uniform inverse-branch sums

Pages 10–14 · Lemma 3.1 and Proposition 3.2 · arXiv:2410.18554v2

The proof bounds the transition integrals uniformly over the admissible inverse branches and separates entrance, interior, and exit contributions. The index ranges keep every iterate in the local domain, and the discarded endpoint terms are lower order under the theorem normalizations.

Sections 4–5Correct and complete

Linearization and flow embedding preserve the asymptotic constants

Pages 15–23 · proofs of Theorems A and B · arXiv:2410.18554v2

In the hyperbolic case the conjugacy converts inverse iteration to multiplication by λ1\lambda^{-1} with uniformly controlled distortion. In the nonhyperbolic case the embedded-flow coordinate converts iteration counts to an integral of the reciprocal vector field. Substitution into the two-sided renewal bounds gives matching limits rather than only order estimates.

03Novelty0 reported findingsNo non-novelty findings

No non-novelty findings.

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Paper
arXiv:2410.18554v2
Authors listed
Jeroen S. W. Lamb, Guillermo Olicón-Méndez, Martin Rasmussen
Audit date
August 18, 2026
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