Sam Raskin - 2/6 Some Aspects of the Geometric Langlands Program

Sam Raskin - 2/6 Some Aspects of the Geometric Langlands Program

🎙 Sam Raskin 👥 79K 📅 March 12, 2026 ⏱ 107 min 👁 1K 📄 lecture course 🧭 2026-08-02
Available in: English (current) Français

Keywords

geometric Langlandsspectral actionlocal systemsHecke functorsD-modules

Summary

This is the second lecture in a series by Sam Raskin on the geometric Langlands program, given at IHES. The lecture begins with a recap of the three settings (de Rham, Betti, étale) and the Hecke functors introduced previously. The main focus is on the spectral action: the action of the category of representations of the dual group on sheaves on the moduli stack of bundles is expected to factor through an action of quasi-coherent sheaves on the stack of local systems. Raskin constructs the evaluation functor from representations to quasi-coherent sheaves on the product of local systems and the curve, and explains how this leads to the spectral action. He discusses the spectral problem in each setting, noting that in the de Rham and Betti worlds the functor is a quotient and admits a fully faithful adjoint. He also addresses questions about generators and the role of chiral algebras. The lecture is technical, aimed at researchers and graduate students, and assumes familiarity with algebraic geometry and representation theory.

169 words

Critical Evaluation

The lecture provides a rigorous and detailed introduction to the spectral action in the geometric Langlands program. Raskin’s exposition is clear, though highly technical, and he takes care to define the necessary constructions, such as the evaluation functor and the spectral action. The argumentation is solid, relying on standard techniques in algebraic geometry and representation theory. The lecture does not cite external sources, but this is typical for a lecture series; the content is based on established research. The title accurately reflects the content. The lecture is well-structured, with a logical flow from recap to new material, and Raskin addresses audience questions effectively. The main limitation is the lack of references for further reading, but this is compensated by the depth of the presentation. Overall, this is a high-quality lecture for an expert audience, providing valuable insights into current research on the geometric Langlands program.

145 words

Title / Content Match

The title accurately reflects the content: a lecture on aspects of the geometric Langlands program.

Quality & Reliability

8/10

Lecture by a leading expert (Sam Raskin, Yale) at IHES, part of a series. Content is technical and rigorous, with formal definitions and proofs sketched. No citations to external sources, but the mathematical content is standard in the field.

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Cited Sources

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Contribution & Novelties

The lecture provides a clear and detailed exposition of the spectral action in the geometric Langlands program, focusing on the construction of the evaluation functor and the spectral problem. It offers insights into the current state of research, particularly the differences between the de Rham, Betti, and étale settings. The lecture is valuable for researchers and graduate students seeking a deeper understanding of this advanced topic.

Pour aller plus loin :

116 words

Radar Profile

The radar profile shows high scores in technical level and information quality, reflecting the advanced and rigorous nature of the lecture. The quantity of information is also high, but the fiability is slightly lower due to the lack of external citations.

Reliability 8/10