arXiv:2208.08911v4
Abstract
In this paper, we study the quasi-stationary behavior of the one-dimensional diffusion process with a regular or exit boundary at 0 and an entrance boundary at . By using the Doob's -transform, we show that the conditional distribution of the process converges to its unique quasi-stationary distribution exponentially fast in the total variation norm, uniformly with respect to the initial distribution. Moreover, we also use the same method to show that the conditional distribution of the process converges exponentially fast in the -norm to the unique quasi-stationary distribution. The rate of convergence of the conditional empirical measure to the quasi-ergodic distribution is also considered. Finally, two examples arising in population dynamics are also given to illustrate the main results.
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Detailed mathematical audit
01Statements3 reported findingsContains wrong statements
The weighted convergence estimate in Theorem 1.2 is not a valid statement for every initial distribution: its Radon-Nikodym derivative need not exist. The uniform total-variation theorem and the quasi-ergodic estimate are not able to be verified from the supplied arguments because two independent steps needed for uniformity over arbitrary initial laws are invalid.
The displayed bound is undefined for allowed initial distributions
Page 5 · Theorem 1.2 and the paragraph immediately preceding it · arXiv:2208.08911v4
The theorem quantifies over every probability measure on but uses . By (2.2) and (2.7), , a non-atomic measure. For the permitted initial law , one has , so and the displayed derivative does not exist. The preceding assertion that every satisfies is therefore false. A substantive repair must either restrict to laws whose -tilt has an density or state a bound in terms of a positive-time regularization; the current universal statement cannot be read literally.
Full paper, version 4 ↗Uniform exponential convergence is not established by the supplied proof
Pages 4-5 and 11-15 · Theorem 1.1 and its proof · arXiv:2208.08911v4
The implication from an entrance boundary at to a bound uniform over all initial laws depends on Proposition 2.2 and on the passage from the estimate (3.1) to (3.8). Proposition 2.2 is not proved, and an norm bound on a function does not control its integral against an arbitrary, possibly singular, probability measure . No independent argument covering the claimed oscillatory exit-boundary regime is supplied. These defects do not disprove the theorem, but they leave the advertised uniform implication unverified.
Champagnat-Villemonais, earlier criteria for uniform convergence ↗The uniform conditional empirical-measure rate remains unverified
Pages 5-6 and 17-19 · Proposition 1.3 and its proof · arXiv:2208.08911v4
The estimate is derived from the strong-ergodicity estimate (5.3), which is exactly the unproved conclusion of Proposition 2.2. Since the claimed constants must be uniform in , ordinary ergodicity of the -process does not fill this dependency. No counterexample was established, but the only supplied proof does not verify the proposition.
Full paper, version 4 ↗02Proofs4 reported findingsContains incorrect or incomplete proofs
The Foster-Lyapunov proof uses a function that is not even continuously differentiable at its splice point and then treats a non-invariant truncated interval as a state space. The proof of Theorem 1.1 also applies an function estimate to arbitrary singular initial laws, and the proof of Theorem 1.2 never repairs the missing Radon-Nikodym derivative.
The Foster-Lyapunov construction does not prove strong ergodicity
Pages 10-11 · Equations (2.12)-(2.18) · arXiv:2208.08911v4
The proposed Lyapunov function equals on and on . Its left derivative at is , whereas its right derivative is ; hence the printed claim and the global generator calculation are false. Independently, inaccessibility of the boundary point does not imply that a diffusion started above never enters . Thus is not an invariant state space, and the constants in (2.17) cannot be replaced by a uniform merely because is arbitrary. Repair classification: No repair supplied; a valid global Lyapunov or minorization argument with constants uniform near is required.
Full paper, version 4 ↗Equation (3.8) does not follow from the estimate
Pages 12-15 · Equations (3.1) and (3.8)-(3.10) · arXiv:2208.08911v4
Equation (3.1) controls . Equation (3.8) instead integrates against and claims a bound uniform in every initial law . An estimate gives no such control when is singular; taking makes the mismatch explicit. Strong total-variation ergodicity would control bounded test functions, but need not be bounded. Repair classification: No repair supplied; a pointwise or appropriately weighted uniform bound is needed.
Full paper, version 4 ↗Positive-time smoothing does not justify the printed initial-density norm
Pages 15-17 · beginning of Section 4 and Equations (4.2)-(4.3) · arXiv:2208.08911v4
The proof says that an infinite density norm makes the theorem trivial, but for a singular initial law the Radon-Nikodym derivative is nonexistent, not an function of infinite norm. The later identity may regularize the law at positive time, yet the final displayed estimate again bounds the regularized norm by , which is unavailable for the stated . Repair classification: No repair supplied; a finite norm at a specified positive time could yield a different estimate with a shifted exponential factor, but it is not the theorem printed.
Full paper, version 4 ↗The bridge estimate depends on the unproved uniform -process bound
Pages 17-19 · Equations (5.3)-(5.4) · arXiv:2208.08911v4
The calculation after (5.3) is algebraically consistent once a uniform exponential bound for the -process is available, but (5.3) is taken directly from Proposition 2.2. Because the proof of that proposition fails at (2.12)-(2.18), the essential input to the conditional empirical-measure estimate is missing. Repair classification: No repair supplied beyond repairing Proposition 2.2.
Full paper, version 4 ↗03Novelty0 reported findingsNo non-novelty findings
No non-novelty findings.