Xuan Yao - Quantification of $C^0$-convergence in dimension 3 (II)

Xuan Yao - Quantification of $C^0$-convergence in dimension 3 (II)

🎙 Xuan Yao (University of Chicago) 👥 81K 📅 October 21, 2026 ⏱ 26 min 👁 12 📄 original study 🧭 2026-10-21
Available in: English (current) Français

Keywords

scalar curvatureC^0 convergenceharmonic functionsquantificationGromov conjecture

Summary

This recorded seminar presents Xuan Yao’s joint work with Liam on quantifying Gromov’s C^0-convergence conjecture for scalar curvature in dimension three. The main theorem states that, given a smooth target metric g0 on the unit ball in R^3, every sufficiently close smooth metric g satisfies a bound on the infimum of its scalar curvature in terms of the scalar curvature of g0 at the origin plus a constant times the square root of the C^0 distance between the metrics. The exponent 1/2 is shown to be sharp. The proof strategy is divided into three steps: first, establishing stability of harmonic functions under C^0 perturbations of the metric; second, constructing a monotone functional built from harmonic functions that detects scalar curvature without sign assumptions; and third, combining gradient estimates with the monotonicity formula to obtain the desired quantification. The talk also discusses several related results, including a measure-convergence theorem under a Lipschitz bound, a continuous positive mass theorem in dimension three, and applications to Gromov’s Euclidean rigidity conjecture. The speaker emphasizes the novelty of the harmonic-function method and mentions alternative approaches such as mu-bubbles and Ricci flow. The presentation is technical and aimed at an audience familiar with geometric analysis.

199 words

Critical Evaluation

Value of the Information & Strength of the Argument

The value of the talk lies in presenting a genuinely new quantitative result with a sharp exponent, achieved through a carefully constructed monotone functional. The argumentation is coherent: each step is motivated, and the speaker explicitly explains how the harmonic-function stability, the given functional, and the double integration technique combine. The discussion of related works places the contribution in a broader context and clarifies how it improves or complements existing methods, such as the mu-bubble technique and Ricci flow. The proof sketch is detailed enough for specialists to follow the main ideas, while acknowledging technical difficulties such as the W^{1,p} estimates and the role of the Riemannian Green’s function.

Scientific Rigor, Source Quality, Title Accuracy

The scientific rigor is high: the presentation is precise, all constants and hypotheses are stated, and the speaker distinguishes carefully between known results and new contributions. The sources mentioned include foundational work by Agostiniani–Mazzieri–Oronzio, Gromov, Gromov–Lawson, Daniel Stern, and others, though no direct links are provided in the video description beyond the Carmin.tv platform. The title accurately reflects the content, and the talk itself is a research seminar rather than a general-audience summary. No public comments were provided to analyze.

204 words

Title / Content Match

The title accurately reflects the content: a research talk on quantifying C^0-convergence of scalar curvature in dimension 3, part II.

Quality & Reliability

8/10

Rigorous research-level mathematical presentation with a proof sketch, explicit constants and references to prior works; no external verification is provided in the description beyond the institutional platform.

Key Moments

Cited Sources

Contribution & Novelties

The main novel contribution is a sharp quantification of C^0-convergence for scalar curvature in dimension three, with explicit exponent 1/2 and achieved via a new monotone functional based on harmonic functions. The method avoids sign assumptions on scalar curvature and extends to related problems such as measure convergence and continuous mass rigidity.

Pour aller plus loin :

91 words

Radar Profile

The radar profile shows very high technical depth and source reliability, with slightly lower information quantity because the talk is a concentrated research presentation. The high technical level is appropriate for the target audience and reflects the originality of the work.

Reliability 8/10