Yunan Yang - Transport- & Measure-Theoretic Approaches Modeling, Identifying, & Forecasting Systems

Yunan Yang - Transport- & Measure-Theoretic Approaches Modeling, Identifying, & Forecasting Systems

🎙 Yunan Yang 👥 42K 📅 October 9, 2025 ⏱ 45 min 👁 457 📄 expert opinion 🧭 2026-08-13
Available in: English (current) Français

Keywords

Koopman operatoroccupation measuretime-delay embeddingTakens' theoreminverse problem

Summary

Yunan Yang presents a series of works on data-driven modeling of dynamical systems using measure-theoretic and transport-based approaches. The talk begins by outlining challenges in inverse problems for ODEs, such as chaos, noise, and derivative estimation. To address these, Yang introduces the concept of occupation measures, which are empirical measures from trajectory data that approximate the invariant measure, and proposes to match these measures via a PDE-constrained optimization framework, using the continuity equation or Fokker-Planck equation. This approach is shown to be robust to noise and slow sampling rates, but suffers from non-uniqueness. To resolve this, Yang employs time-delay embedding, based on Takens’ theorem, and shows that matching occupation measures in delay coordinates can recover the dynamics up to topological conjugacy, and with multiple observables, uniqueness on the support. The talk also covers a theoretical result that the pushforward action of an embedding on probability measures is itself an embedding, providing a rigorous foundation for the method. Numerical examples include the Lorenz system, the Kuramoto-Sivashinsky equation, and a Hall effect thruster application. The presentation concludes with a discussion of the Distributional Koopman Operator (DKO), which extends Koopman analysis to random dynamical systems using distribution data.

195 words

Critical Evaluation

Value of the Information & Strength of the Argument

The talk presents a coherent and well-motivated research program. The value lies in addressing practical challenges in data-driven modeling, particularly when data quality is poor. The argumentation is solid: the speaker clearly identifies limitations of existing methods (e.g., sensitivity to noise and sampling rate) and proposes a novel measure-theoretic framework that leverages ensemble information. The theoretical contributions, such as the embedding result for pushforward actions on probability measures, are significant. The numerical examples support the claims, showing improved robustness in noisy and slow-sampling scenarios. However, the presentation is dense and assumes a high level of mathematical background, which may limit accessibility. The speaker does not provide a critical comparison with all alternative methods, but the evidence presented is convincing.

Scientific Rigor, Source Quality, Title Accuracy

The talk is scientifically rigorous, with clear definitions and theoretical statements. The speaker cites collaborators and mentions specific papers, but no external references are provided in the description. The title accurately reflects the content. The talk is part of an IPAM workshop, which lends credibility. However, the lack of citations in the description limits the ability to verify sources. The speaker does not discuss potential limitations of the proposed methods in depth, but the overall rigor is high.

212 words

Title / Content Match

The title accurately reflects the content, which focuses on transport- and measure-theoretic methods for modeling, identifying, and forecasting dynamical systems.

Quality & Reliability

8/10

Talk by a Cornell professor presenting original research with theoretical results and numerical examples, but limited external verification and no peer-reviewed citations in the description.

Key Moments

Cited Sources

Concurring Sources

Contribution & Novelties

The talk presents a novel framework for data-driven modeling of dynamical systems by shifting from Lagrangian particle trajectories to Eulerian probability distributions. The key innovation is the use of occupation measures and PDE-constrained optimization to infer system parameters robustly, even with noisy or slow-sampled data. The introduction of time-delay embedding into measure matching addresses the non-uniqueness issue, and the theoretical result that pushforward actions of embeddings on probability measures are themselves embeddings provides a rigorous foundation. The Distributional Koopman Operator (DKO) extends Koopman analysis to random dynamical systems, enabling analysis without trajectory data.

Pour aller plus loin :

  • Takens’ theorem — Foundational result on delay embedding, directly relevant to the talk’s use of time-delay coordinates.
  • Koopman operator — The talk builds on Koopman theory; this page provides background.
  • Optimal transport — The talk uses transport-based methods; this page introduces the theory.
  • Fokker-Planck equation — The talk mentions this equation for modeling stochastic dynamics.

153 words

Radar Profile

The radar profile shows high scores in technical level and information quantity, indicating a dense, expert-level presentation. The lower score in reliability reflects the lack of external citations and the reliance on the speaker's own claims. The overall profile suggests a highly specialized talk suitable for researchers in dynamical systems and applied mathematics.

Reliability 7/10