Pages
Lecture 1: Manifolds
Lecture 2: Lie Groups I
Lecture 3: Lie Groups II
Lecture 4: Homogeneous Spaces and Lie Group Actions
Problem set 1 due
Lecture 5: Tensor Fields
Lecture 6: Classical Lie Groups
Problem set 2 due
Lecture 7: The Exponential Map of a Lie Group
Lecture 8: Lie Algebras
Problem set 3 due
Lecture 9: Fundamental Theorems of Lie Theory
Lecture 10: Proofs of the Fundamental Theorems of Lie Theory
Problem set 4 due
Lecture 11: Representations of Lie Groups and Lie Algebras
Lecture 12: The Universal Enveloping Algebra of a Lie Algebra
Problem set 5 due
Lecture 13: The Poincare-Birkhoff-Witt Theorem
Lecture 14: Free Lie Algebras and the Baker-Campbell-Hausdor Formula
Problem set 6 due
Lecture 15: Solvable and Nilpotent Lie Algebras and Theorems of Lie and Engel
Lecture 16: Semisimple and Reductive Lie Algebras, the Cartan Criteria
Problem set 7 due
Lecture 17: Proofs of the Cartan Criteria and Properties of Semisimple Lie Algebras
Lecture 18: Extensions of Representations, Whitehead’s Theorem, and Compete Reducibility
Problem set 8 due
Lecture 19: Structure of Semisimple Lie Algebras I
Lecture 20: Structure of Semisimple Lie Algebras II
Problem set 9 due
Lecture 21: Root Systems
Lecture 22: Properties of the Weyl Group
Problem set 10 due
Lecture 23: Dynkin Diagrams
Lecture 24: Construction of a Semisimple Lie Algebra from a Dynkin Diagram
Problem set 11 due
Lecture 25: Representation Theory of Semisimple Lie Algebras
Lecture 26: The Weyl Character Formula
Problem set 12 due
[LN] = Lecture Notes
[K] = Alexander Kirillov Jr.’s An Introduction to Lie Groups and Lie Algebras.
Use Problem sets (PDF) to complete the problems assigned below.
Homework 1: K 2.1–2.6
Additional Exercises 1: LN 1.10
Homework 2: K 2.7–2.16
Additional Exercises 2: LN 3.4, 3.6, and 3.9
Homework 3: LN 6.2, 6.4, 6.5, and 6.14–6.17
Additional Exercises 3: LN 6.1, 6.9, and 6.11
Homework 4: K 3.1, 3.5–3.9, and 3.11
Additional Exercises 4: LN 3.12 and 4.3
Homework 5: K 3.13, and 3.15–3.19
Additional Exercises 5: LN 5.7 and 5.11
Homework 6: K 4.2, 4.4, 4.7 and 4.9
Additional Exercises 6: LN 7.7 and 8.11
Homework 7: K 4.1, 4.11, 4.12, and 5.1–5.7
Additional Exercises 7: LN 9.2 and 9.17
Homework 8: K 6.1–6.6; LN 11.19, 12.7, 15.2, and 15.5
Additional Exercises 8: LN 14.15 and 15.7
Homework 9: LN 11.4, 11.20, 15.11, and 15.16
Additional Exercises 9: LN 16.13 and 18.3
Homework 10: K 7.1, 7.2, 7.4, 7.5, and 7.8–7.11
Additional Exercises 10: LN 22.4
Homework 11: K 7.7, and 7.12–7.16
Additional Exercises 11: LN 22.18
Homework 12: LN 23.9, 23.10, 23.12, and 23.13
Additional Exercises 12: LN 23.16, 23.17, and 26.7
Course Meeting Times
Lectures: 2 sessions / week, 80 minutes / session
Prerequisites
- 18.701 Algebra I or 18.703 Modern Algebra
- Real Analysis—either 18.100A, 18.100B, 18.100P, or 18.100Q
Course Overview
We will discuss both Lie algebras and Lie groups together in both halves. (These subjects are so intimately related that it is more natural to study them together.) But still the first semester will be mostly algebra while the second one will involve a bit more geometry and analysis. There will be a lot of emphasis on examples.
In the first half (18.745) we will essentially follow Alexander Kirillov Jr.’s An Introduction to Lie Groups and Lie Algebras (PDF), excluding the more advanced material on representations of Lie groups (such as Haar measure, Peter-Weyl theorem, etc.), but with more detailed treatment of Lie algebras. Namely, chapters 2 and 3 (without proofs of the harder theorems, such as Lie’s third theorem), 4.1 to 4.4, and chapters 5 to 8, classification of simple complex Lie algebras with proof. The course also discusses universal enveloping algebras, the Poincare-Birkhoff-Witt theorem, free Lie algebras, and the Campbell-Hausdorff formula.
In the second half (18.755) we will give a more in-depth treatment of Lie groups (relying on what was done in the first half). Topics will include representations of GL(n) and other classical groups; fundamental and minuscule representations; applications of representation theory of Lie groups to quantum mechanics of the hydrogen atom; Haar measure and integration on compact groups; representations of compact (in particular, finite) groups; the Peter-Weyl theorem with proof; maximal tori in compact Lie groups; complex reductive Lie groups; Borel and parabolic subgroups; flag variety; classification of real reductive groups and their structure (maximal tori, maximal compact subgroups, Cartan and Iwasawa decompositions); cohomology of Lie groups and Lie algebras; classification of finite-dimensional simple complex Lie algebras with proof; Levi decomposition; proofs of the third fundamental theorem of Lie theory; Ado’s theorem.
Assignments
Homework will be assigned weekly (first one after 1 week of class) and due in one week. It contains a lot of important material.
Grading
The grade will be given solely on the basis of homework.