Schemes 15: Quasicompact, Noetherian

Schemes 15: Quasicompact, Noetherian

🎙 Richard E Borcherds 👥 82K 📅 July 11, 2020 ⏱ 26 min 👁 3K 📄 lecture 🧭 2026-08-17
Available in: English (current) Français

Keywords

quasicompactNoetherianschemeaffine schemelocal property

Summary

This lecture is part of an online algebraic geometry course on schemes, based on chapter II of Hartshorne’s ‘Algebraic Geometry’. The speaker defines quasicompact and Noetherian schemes, explains the motivation behind these definitions, and proves that being locally Noetherian is a local property. He begins by recalling that affine schemes are quasicompact, then introduces the notion of a Noetherian topological space and explains why the definition of a Noetherian scheme is not simply that its underlying topological space is Noetherian. The lecture covers examples, including projective varieties and the Hilbert scheme, and discusses the split in algebraic geometry between those who work with Noetherian schemes and those who do not. The speaker also mentions Nagata’s example of a Noetherian ring of infinite dimension and the concept of excellent rings as a potential solution to the problem of finding a good finiteness condition.

142 words

Critical Evaluation

Value of the Information & Strength of the Argument

The lecture provides a clear and rigorous introduction to quasicompact and Noetherian schemes. The speaker carefully motivates each definition and proves key properties, such as the fact that affine schemes are quasicompact and that locally Noetherian is a local property. The argumentation is solid, with proofs that are concise but complete. The discussion of the split in algebraic geometry between Noetherian and non-Noetherian schemes adds context and depth, and the mention of Nagata’s example illustrates the subtlety of the subject.

Scientific Rigor, Source Quality, Title Accuracy

The lecture is based on Hartshorne’s ‘Algebraic Geometry’, a standard reference in the field. The speaker is a well-known mathematician, and the content is mathematically accurate. The title accurately reflects the content, which focuses on quasicompact and Noetherian schemes. The lecture is well-structured and the proofs are rigorous. No external sources are cited beyond the textbook, but the lecture is self-contained and the mathematical reasoning is sound.

162 words

Title / Content Match

The title accurately reflects the content, which focuses on defining and discussing quasicompact and Noetherian schemes.

Quality & Reliability

9/10

Lecture by a renowned mathematician, based on Hartshorne's textbook, with rigorous definitions and proofs. The content is mathematically sound and well-structured.

Key Moments

Cited Sources

Concurring Sources

  • Algebraic Geometry — The lecture follows the definitions and results from this textbook.

Contribution & Novelties

The lecture provides a clear and rigorous introduction to quasicompact and Noetherian schemes, with careful motivation and proofs. It also discusses the historical and practical split in algebraic geometry regarding the use of Noetherian hypotheses, and mentions Nagata’s example of a Noetherian ring of infinite dimension, which is a subtle counterexample.

Pour aller plus loin :

87 words

Radar Profile

The radar profile shows high scores in quality of information, technical level, and reliability, with a slightly lower score in quantity of information due to the focused scope of the lecture. This indicates a highly technical and reliable source, ideal for advanced students.

Reliability 9/10