Sam Raskin - 3/6 Some Aspects of the Geometric Langlands Program

Sam Raskin - 3/6 Some Aspects of the Geometric Langlands Program

🎙 Sam Raskin 👥 80K 📅 March 13, 2026 ⏱ 126 min 👁 719 📄 lecture course 🧭 2026-08-06
Available in: English (current) Français

Keywords

Eisenstein seriesLanglands functorD-modulesparabolic inductionspectral action

Summary

This is the third lecture in a series by Sam Raskin on the Geometric Langlands Program, delivered at IHES. The lecture focuses on the theory of Eisenstein series and its role in the geometric Langlands correspondence. Raskin begins by defining the Eisenstein series functor for a Levi subgroup M of a reductive group G, using a parabolic P. He explains that this functor is left adjoint to the constant term functor, and discusses the technical conditions under which it is well-defined, particularly in the D-module setting, mentioning the Drinfeld compactification and ULA sheaves. He then introduces the spectral counterpart, an Eisenstein series functor on the Langlands dual side, and states a theorem that the geometric Langlands functor intertwines these two operations. He emphasizes the formal similarity but geometric difference between the automorphic and spectral sides. The lecture includes a discussion of the proof strategy, involving the Drinfeld compactification and the geometry of the relevant moduli stacks. The talk is highly technical, aimed at researchers and graduate students in algebraic geometry and representation theory.

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Critical Evaluation

The lecture is a masterclass in advanced mathematics, delivered by a leading expert. The content is rigorous and precise, with careful attention to technical hypotheses. Raskin’s explanations are clear, though the material is inherently difficult. He provides motivation and context, connecting the geometric Langlands program to classical representation theory. The proof outline is insightful, highlighting the key geometric ideas. The lecture is well-structured, building on previous talks and setting up future ones. The interaction with the audience shows a deep engagement with the subject. The only minor criticism is that the lecture assumes a high level of background knowledge, but this is appropriate for the intended audience. The sources cited are standard references in the field, and the speaker’s authority is unquestionable. Overall, this is an excellent lecture that provides a deep insight into current research in geometric Langlands.

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Title / Content Match

The title accurately describes the content: a lecture on aspects of the Geometric Langlands Program, specifically Eisenstein series and spectral actions.

Quality & Reliability

9/10

Lecture by a leading expert (Sam Raskin, Yale) at IHES, part of a series. The content is highly technical and rigorous, with precise mathematical definitions and references to established work (e.g., Braverman-Gaitsgory). The video is a formal academic lecture, not popularization, and the speaker is clearly authoritative. Minor deductions for lack of visual aids and occasional informal asides.

Key Moments

Cited Sources

  • Carmin.tv — Video platform for mathematical sciences, hosting this lecture.

Concurring Sources

Contribution & Novelties

This lecture provides a clear and detailed exposition of the role of Eisenstein series in the geometric Langlands program, emphasizing the intertwining property with the Langlands functor. It offers insights into the technical challenges and the geometric ideas behind the proof, making it a valuable resource for researchers.

Pour aller plus loin :

90 words

Radar Profile

The radar profile shows very high scores in all dimensions, indicating a lecture that is both information-dense and technically rigorous. The balance between quantity and quality is excellent, with a slight emphasis on technical depth.

Reliability 9/10