arXiv:2610.25559v1
Abstract
We study the statistical properties of partially hyperbolic diffeomorphisms with a two-dimensional center exhibiting mixed behavior, without assuming a dominated splitting inside the center. We introduce the notion of an expanding on average for partially hyperbolic diffeomorphism and, under a center jacobian assumption, we prove the existence of finitely many ergodic hyperbolic SRB measures, and show the strong positive recurrence property, which implies that each SRB measure, up to a period, satisfies exponential decay of correlations, among other strong statistical laws. We apply our results to several examples.
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Detailed mathematical audit
01Statements2 reported findingsNo statement issues found
The finiteness and full-basin theorem for hyperbolic SRB measures, continuity of the two center exponents, strong statistical properties, and robustness consequences are stated with the required two-dimensional center, regularity, bunching, average-expansion, and positive-gap assumptions. No false central statement was found.
Average expansion and a positive exponent gap give uniform hyperbolicity and continuous center exponents
PDF pages 3–4, 11–27, and 45–58 · Theorems A–B and Sections 3–7 · arXiv:2610.25559v1
Average expansion forces the top center exponent of every unstable Gibbs measure above the optimal constant, while the determinant bound defining the gap forces the bottom exponent below its negative. Projective unstable Gibbs measures select the positive Oseledets direction uniquely; compactness under perturbation then gives continuity of the top exponent, and the determinant identity gives continuity of the bottom one. Uniform Pesin blocks yield finiteness, while effective hyperbolicity supplies existence and the full-basin argument.
The strong positive recurrence conclusion follows from uniform exponent control
PDF pages 4 and 59–68 · Theorem C and Section 8 · arXiv:2610.25559v1
Measures in a fixed homoclinic class with geometric pressure tending to zero converge to unstable Gibbs measures, and their center exponents converge as well. The uniform-Pesin-block criterion therefore rules out escape from every fixed block, establishing strong positive recurrence. The cited structural theorem then gives the finite cyclic decomposition and the listed statistical laws.
02Proofs3 reported findingsNo proof issues found
The principal proof chains are mathematically coherent. One harmless reversed inequality in the choice of an auxiliary positive parameter has a uniquely determined correction; with that typographical correction, the stable-direction estimate and all downstream arguments are valid. No substantive incorrectness or incompleteness was found.
The admissible range for the auxiliary parameter is reversed in print
PDF page 38 · proof of Theorem 5.1 immediately after equation (5.4) · arXiv:2610.25559v1
The proof has fixed and obtains the decay exponent . The printed instruction is impossible because its right-hand side is negative. It must read . This correction is mechanically determined by the preceding parameter ranges and makes the displayed geometric-series estimate decay; it does not change the argument or any theorem statement.
Stable directions and uniform Pesin blocks support the finiteness argument
PDF pages 35–49 · Sections 5–6 · arXiv:2610.25559v1
The ratio of singular values is summable at almost every point on each unstable leaf, so the most-contracted directions converge and contract at rate at least the exponent gap; every transverse direction expands. Continuity of the exponent sums over the compact unstable-Gibbs family yields a common Pesin block of arbitrarily large measure. Two limiting SRB measures charging the same sufficiently small block ball are homoclinically related and hence equal, proving finiteness.
Effective hyperbolicity yields existence and full-volume basins
PDF pages 50–58 · Section 7 · arXiv:2610.25559v1
Positive-density simultaneous Pliss times control expansion, contraction, and angles on a transverse disk, meeting the cited effective-hyperbolicity criterion and producing an SRB measure. Repeating the construction inside a hypothetical positive-volume complement of all basins yields a nonzero SRB component whose stable saturation meets that complement in positive volume, a contradiction.
03Novelty0 reported findingsNo novelty concerns found
No non-novelty findings.