Decay of correlations for partially hyperbolic skew-products

Decay of correlations for partially hyperbolic skew-products

🎙 Prof. Wael Bahsoun 👥 8K 📅 August 21, 2026 ⏱ 40 min 👁 25 📄 expert opinion 🧭 2026-08-21
Available in: English (current) Français

Keywords

decay of correlationspartially hyperbolicskew-productsphysical measuretransfer operator

Summary

The talk by Prof. Wael Bahsoun presents a study on decay of correlations for partially hyperbolic skew-products, joint with José Alves. The motivation comes from the heterochaos baker map, a family of maps with a parameter that can be mostly contracting, mostly expanding, or neutral. The main result establishes the existence of a unique physical measure and exponential decay of correlations for Lipschitz observables under assumptions of a nice expanding base map and mostly contracting fibers. The proof uses a transfer operator acting on fiber measures, a contraction estimate, and a Lasota-Yorke type inequality to obtain regularity of the fixed point. Applications include non-uniformly contracting Viana-like maps and dissipative heterochaos baker maps. The talk concludes with open questions on the mostly expanding case, the neutral case, and linear response.

129 words

Critical Evaluation

Value of the Information & Strength of the Argument

The talk presents a rigorous mathematical result with a clear proof strategy. The argumentation is solid, building on known techniques (transfer operators, Lasota-Yorke inequalities) and extending them to a new setting. The value of the information is high for specialists in dynamical systems, as it addresses a gap in the literature on partially hyperbolic systems with non-uniform contraction. The speaker carefully explains the assumptions and the logic of the proof, making the argument accessible to an expert audience.

Scientific Rigor, Source Quality, Title Accuracy

The talk is scientifically rigorous, based on a joint work with José Alves. The speaker cites relevant literature, including works by Takahashi, Tsujii, and others. The title accurately reflects the content. The sources are appropriate for the topic, and the presentation is consistent with current research in the field. The talk is part of a workshop at the Isaac Newton Institute, which adds to its credibility.

159 words

Title / Content Match

The title accurately reflects the content, which focuses on decay of correlations for partially hyperbolic skew-products.

Quality & Reliability

8/10

Talk by a recognized expert in dynamical systems, based on a joint work with José Alves, presenting rigorous mathematical results with a clear proof sketch. The content is technical and precise, but the format (seminar talk) limits the depth of verification.

Key Moments

Cited Sources

Concurring Sources

  • Takahashi, Y. (2018) 'Decay of correlations for a family of partially hyperbolic maps' — Cited in the talk as prior work on the heterochaos baker map.
  • Takahashi, Y., & Tsujii, M. (2020) 'Sharp polynomial decay of correlations for a family of partially hyperbolic maps' — Cited in the talk for the neutral case.

Contribution & Novelties

The talk presents new results on decay of correlations for partially hyperbolic skew-products with mostly contracting fibers, extending previous work by Takahashi and others. The main novelty is the treatment of non-uniform contraction in the fibers, leading to a general theorem applicable to various examples. The proof technique using a transfer operator on fiber measures and a Lasota-Yorke type inequality is a contribution in itself.

Pour aller plus loin :

  • Partially hyperbolic dynamical systems — Background on partially hyperbolic systems.
  • Transfer operator — The main tool used in the proof.
  • Physical measure — Definition and relevance of physical measures.

99 words

Radar Profile

The radar profile shows high scores in information quality and technical level, reflecting the advanced mathematical content. The quantity of information is moderate, as the talk is a seminar presentation with a focused scope. The overall reliability is high, consistent with the speaker's expertise and the institutional setting.

Reliability 8/10