arXiv:2608.05649v1
Abstract
We adapt the theory of Ruelle-Pollicott resonances to annealed random dynamical systems generated by independent and identically distributed families of maps. Introducing annealed transfer and Koopman operators, we define resonances as elements of the point spectrum of the associated operators and establish a decorrelation formula relating these resonances to the asymptotic decay of annealed correlations. We then study several classes of systems for which the theory can be made explicit. First, we consider a family of piecewise expanding Markov maps of the interval, we construct Banach spaces adapted to the dynamics and obtain a complete description of the annealed resonance spectrum. Then we investigate an inverse spectral problem, proving realisability results for prescribed collections of complex numbers as resonances of suitably constructed annealed dynamical systems.
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Detailed mathematical audit
01Statements3 reported findingsContains wrong statements
The Blaschke-product spectrum and the full-resonance conclusion for the interval families are correct. The general Jordan expansion is false when its index is identified with geometric multiplicity, and the claimed mixing corollary is false under transitivity alone.
The annealed Blaschke spectrum is correct
Pages 8 and 24–27 · Theorems A and 11 · arXiv:2608.05649v1
The common Hilbert basis makes the averaged Koopman operator compact and triangular. Its nonzero diagonal entries are , , and . Compactness excludes any further nonzero spectrum, and the row structure gives the stated algebraic and geometric multiplicities after the proof repair recorded below. The deterministic matrix formula used before averaging agrees with the cited analytic-Anosov calculation.
Slipantschuk–Bandtlow–Just, Complete spectral data for analytic Anosov maps of the torus ↗Geometric multiplicity does not determine the polynomial powers in a Jordan expansion
Pages 8–9 and 30–32 · Proposition 2.2(2), Lemma A.2 and equations (54)–(64) · arXiv:2608.05649v1
The statements set equal to geometric multiplicity and truncate the terms at . Take the constant Banach scale and All compactness, spectral-gap, inclusion, density, and generalized-eigenspace hypotheses hold, but the geometric multiplicity is one while The required contribution is absent from the printed formula. Replace geometric multiplicity by the maximal Jordan-block size, or sum separately over the blocks; with that correction, the intended decorrelation expansion is valid.
Transitivity does not imply mixing
Pages 9, 12, and 20–21 · Theorem B, Theorem 5 and Corollary 7 · arXiv:2608.05649v1
Use a deterministic one-point base and the four Markov intervals . Define with slope so that each of maps onto and each of maps onto . This is a transitive piecewise-linear expanding Markov map satisfying every displayed hypothesis, but its irreducible transition matrix has period two. Lebesgue measure is invariant and satisfies , so and the system is not mixing. Equivalently, the transfer operator has eigenvalue . The full decorrelation formula remains correct because that peripheral resonance can be included; only the asserted mixing and spectral-gap consequence fails.
02Proofs5 reported findingsContains incorrect or incomplete proofs
The proofs contain a false Perron–Frobenius inference, an incorrect Jordan-multiplicity argument, and an unproved orthogonality step in the averaged abstract decomposition. The core compactness and interval quasi-compactness arguments are otherwise repairable.
Irreducibility is incorrectly strengthened to primitivity
Pages 20–21 · proof of Corollary 7 · arXiv:2608.05649v1
Perron–Frobenius gives simplicity of the eigenvalue for an irreducible stochastic matrix, but it does not put every other eigenvalue strictly inside the unit circle. An irreducible matrix of period has peripheral th roots of unity. The explicit period-two map in the Statements finding realizes exactly this obstruction. A repair requires an aperiodicity or primitivity hypothesis; it cannot be obtained from the stated transitivity assumption.
The Jordan calculation uses the wrong multiplicity
Pages 30–31 · proof of Lemma A.2 · equations (55)–(59) · arXiv:2608.05649v1
A nilpotent part does not satisfy when is merely the geometric multiplicity. Its nilpotency order is the largest Jordan-block size. Replacing by that order and expanding gives the required finite polynomial-exponential expansion. This repair propagates through Proposition 2.2 and Theorem 5 without changing the existence of full resonances.
The displayed basis vectors are not eigenvectors
Page 27 · proof of Theorem 11 · arXiv:2608.05649v1
The proof says that is an eigenvector, but equation (34) gives up to normalization, which is not generally a scalar multiple of . The multiplicity conclusion is nevertheless recoverable. Each row carrying a nonzero diagonal value has no off-diagonal entry, so its coordinate functional is an eigenvector of . For , is Fredholm of index zero; hence . The triangular finite sections give the algebraic multiplicity as the number of occurrences, so the geometric multiplicity equals it.
Orthogonality does not follow by averaging the fibre decompositions
Pages 8 and 31–32 · Proposition 2.2(1) and its proof · arXiv:2608.05649v1
The proof shows only that is a compact perturbation of an operator whose norm is bounded by . It then asserts an orthogonal decomposition . Pointwise relations do not imply , because cross terms with different remain. A spectral projection can give an orthogonal invariant splitting, but the proof does not establish the separately claimed one-step operator-norm bound for its remainder.
Two notation defects have unique harmless corrections
Pages 6–7 and 15–17 · Definition 4 and equations (16), (20) · arXiv:2608.05649v1
In Definition 4, replace the printed remainder by . In the Lasota–Yorke displays, the factor must multiply , while the bounded coefficient multiplies . The calculations immediately below the displays derive exactly these corrected inequalities, which are the form needed for the essential-spectral-radius argument.
03Novelty0 reported findingsNo non-novelty findings
No non-novelty findings.