arXiv:2503.06597v5

Exchange of Intervals and Intrinsic Ergodicity of the Negative Beta shift

Florent Nguema Ndong, Anne Bertrand-Mathis

math.DS11K1611B0537A0537A2537B10

Abstract

This work highlights a peculiar phenomenon of interval exchange. Considering a real number beta less than -1, the negative beta-shift is coded if and only if its absolute value is greater than the golden ratio. We study an increasing sequence of algebraic integers with limit-1 and the absolute value of the first term equals to the golden ratio such that for a base x taken in the interval of consicutive terms of this sequence, the measure of the maximal entropy is carried by the image of a beta-shift, with the golden ratio les than the absolute value of beta, under the mapping of an injective substitution.

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Audit summary

Audited against arXiv v5

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.

Current report

Detailed mathematical audit

Generated August 18, 2026
01Statements2 reported findingsCorrect

The coding classification, intrinsic ergodicity, mixing maximal-entropy measure, and support description for negative beta shifts are correct in the parameter ranges stated in version 5.

Theorems 1–5Correct

The code and its Champernowne measure describe the maximal component

Pages 10–13 and 25–30 · Theorems 1–5 · arXiv:2503.06597v5

The alternating-order characteristic sequence determines admissibility, and the substitution φ(k)=1(00)k\varphi(k)=1(00)^k transfers the endpoint expansions between successive parameter intervals. The resulting prefix code is positive recurrent at entropy logβ\log|\beta|, while all hybrid and intransitive components carry strictly smaller entropy. Hence the coded component supports the unique maximal-entropy measure; the gcd-one computation gives mixing.

Full paper, version 5
Theorems 3–5Correct

Coding, intrinsic ergodicity, and support of the maximal measure are consistent

Sections 4–6 · arXiv:2503.06597v5

The prefix code is positive recurrent in precisely the parameter regime stated, giving a unique maximal-entropy Markov measure. The substitution/morphism maps it to the negative-β\beta shift, and the irreducible coded component has full entropy, so the announced support and mixing conclusions follow.

02Proofs2 reported findingsCorrect

The combinatorial coding, recurrence, entropy comparison, and uniqueness proofs are correct and complete.

Sections 3–5Correct and complete

Substitutions preserve the alternating order and isolate the maximal component

Pages 8–31 · Sections 3–5 · arXiv:2503.06597v5

Parity in the alternating order is tracked in each substitution case, the prefix and suffix decompositions are unambiguous, and the generating series has the required positive-recurrence root. Nullity of hybrid sequences is proved for every invariant measure before the support conclusion is used, and the entropy comparison leaves a single maximal component.

Sections 4–6Correct and complete

Prefix-code recurrence and the entropy comparison close the measure argument

Pages 19–35 · arXiv:2503.06597v5

The alternating-order combinatorics identifies admissible return words without overlap. Their generating series has the required recurrence radius, yielding the Champernowne/Markov measure; entropy of all residual components is strictly smaller, which proves uniqueness and allows the coding map to transfer mixing and support.

03Novelty0 reported findingsNo non-novelty findings

No non-novelty findings.

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Paper
arXiv:2503.06597v5
Authors listed
Florent Nguema Ndong, Anne Bertrand-Mathis
Audit date
August 18, 2026
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