arXiv:2606.06785v1

Empirical Transfer Operators and Finite-Sample Change Detection for Noisy Expanding Interval Maps

Aparna Rajput

stat.MLcs.LGmath.DS37A3060J1062M10

Abstract

We study finite-sample change detection for one-dimensional noisy dynamical systems using partition-based empirical approximations of stationary behaviour. Given observations from an interval-valued process, we partition the state space, estimate a finite transition matrix from observed transitions between partition elements, and apply a small Doeblin-type regularisation to ensure a unique stationary distribution. From an initial reference segment, we compute a baseline empirical stationary distribution π^0,ρ\widehatπ_{0,ρ}. For each later sliding window, we compute π^t,ρ\widehatπ_{t,ρ} and define the score St=π^t,ρπ^0,ρ1. S_t=\|\widehatπ_{t,ρ}-\widehatπ_{0,ρ}\|_1. Large values of StS_t indicate a change in stationary behaviour relative to the baseline. The statistic detects changes in invariant density or stationary law, but not all possible changes in transition dynamics. Under explicit assumptions on empirical transition concentration, finite-state stationary distribution stability, partition approximation, regularisation bias, and noise stability, we derive a finite-sample bound for the empirical stationary density. The bound separates sampling error, regularisation bias, partition approximation error, and noise bias. We then obtain a single-window false-alarm guarantee and a sufficient detection condition when the invariant density changes by more than the estimation error. We illustrate the method on synthetic noisy beta-map change-point experiments.

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Audited against arXiv v1

Not a correctness certificate. A “Correct” result may include yellow typos or minor formal corrections that do not affect substantive soundness. It means this audit found no unresolved substantive error under the stated criteria; it does not replace expert scrutiny or formal verification.

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Detailed mathematical audit

Generated August 18, 2026
01Statements4 reported findingsCorrect

The finite-sample approximation bounds for regularized empirical transition operators and the resulting false-alarm and detection guarantees are correct under the paper's explicit concentration, partition, regularization-bias, noise-stability, and sampling assumptions.

Theorem 3.10Correct

Finite-sample invariant-density error bound

Pages 8–11 · Lemma 3.6, Proposition 3.9 and Theorem 3.10 · arXiv:2606.06785v1

The assumed entrywise transition-probability concentration is lifted by a union bound to the matrix norm used in the proof. Doeblin regularization writes the transition matrix as (1ρ)P~+ρJN(1-\rho)\widetilde P+\rho J_N; on zero-sum row vectors this gives contraction factor 1ρ1-\rho and hence the perturbation factor 1/ρ1/\rho. Separating sampling, regularization bias, partition approximation, and observation-noise terms gives the stated error radius and probability bound.

Proposition 3.9Correct

Stationary-vector stability under Doeblin regularization

Pages 9–10 · Proposition 3.9 · arXiv:2606.06785v1

For two regularized row-stochastic matrices P,QP,Q, the difference x=πQπPx=\pi_Q-\pi_P and forcing term e=πQ(QP)e=\pi_Q(Q-P) both have coordinate sum zero. Iterating x=e+xPx=e+xP and using yP1(1ρ)y1\|yP\|_1\leq(1-\rho)\|y\|_1 on that subspace gives the convergent geometric series and the bound πQπP1ρ1QProw,1.\|\pi_Q-\pi_P\|_1\leq\rho^{-1}\|Q-P\|_{\mathrm{row},1}.

Change-detection guaranteesCorrect

False-alarm and detection bounds

Pages 11–14 · Sections 4.1–4.3 · arXiv:2606.06785v1

Under the null, the two empirical stationary-density estimates differ by at most the sum of their confidence radii, giving the stated threshold and false-alarm probability. Under the alternative, the triangle inequality subtracts the same radii from the population separation. The advertised detection conclusion is therefore conditional on a separation larger than the finite-sample uncertainty, exactly as stated.

Corollary 4.2 and Theorem 4.4Correct

Multiple-window control and asymptotic consistency

Pages 13–14 · arXiv:2606.06785v1

The familywise false-alarm estimate is a direct union bound over the finite set of windows and therefore remains valid even for overlapping windows. Under the sequences assumed in Theorem 4.4, both confidence radii and both exponential tail bounds vanish. The null score then stays below threshold with probability tending to one, while any fixed L1L^1 separation eventually satisfies the detection margin.

02Proofs1 reported findingCorrect

Conditional on the stated concentration and approximation assumptions, the perturbation and testing arguments are complete. All rates are conditional rather than asymptotic universality claims, and the error radii used in the change-detection step match those established for the density estimator.

Section 3 and detection sectionCorrect and complete

Concentration-to-detection proof chain

Pages 7–14 · arXiv:2606.06785v1

The proof fixes the finite partition, applies the union bound at the stated matrix dimension, and uses the zero-sum contraction created by the Doeblin term to compare stationary vectors. Under the null and alternative, the two estimator-error events are combined by an ordinary union bound; independence between the baseline and window events is not required.

03Novelty0 reported findingsNo non-novelty findings

No non-novelty findings.

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Paper
arXiv:2606.06785v1
Authors listed
Aparna Rajput
Audit date
August 18, 2026
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