The main subjects of this course are the notion and some of the basic properties of group representations. In this course, we first introduce the notions of irreducible representations of groups and endomorphism algebras of group representations, and then explain Schur's lemma, which is an important result closely related to these notions. Next, we introduce group characters, and then explain the orthogonality relations for them. Also, we explain the irreducible decomposition of the group algebra of a finite group. Finally, we introduce tensor products and induced representations for group representations, and then explai n the Frobenius reciprocity, which is an important result closely related to these notions. This course is a continuation of "Advanced courses in Algebra C" in the third quarter.
The therory of group representations is not just a typical example of the general theory of modules over a ring, but also has a wide variety of applications in physics and chemistry other than mathematics. The aim of this course is to make students familiar with basic methods in group representations and enable them to make use of these correctly.
By the end of this course, students will be able to:
1) Understand the notions of irreducible representations of groups and endomorphism algebras of group representations, and make use of Schur's lemma.
2) Explain the definition of group characters, and make use of the orthogonality relations for them correctly.
3) Understand the irreducible decomposition of the group algebra of a finite group.
4) Understand the notions of tensor products and induced representations for group representations, and make use of the Frobenius reciprocity.
Schur's lemma, Maschke's theorem, group characters, orthogonality relations for group characters, irreducible decomposition of the group algebra, tensor products of group representations, induced representations, Frobenius reciprocity
✔ Specialist skills | Intercultural skills | Communication skills | Critical thinking skills | Practical and/or problem-solving skills |
Standard lecture course.
Course schedule | Required learning | |
---|---|---|
Class 1 | Schur's lemma and Maschke's theorem | Details will be provided during each class session. |
Class 2 | Commutant and endomorphism algebras | Details will be provided during each class session. |
Class 3 | Characters of group representations | Details will be provided during each class session. |
Class 4 | Inner products of characters and orthogonality relations | Details will be provided during each class session. |
Class 5 | Decomposition of the group algebra of a finite group | Details will be provided during each class session. |
Class 6 | Tensor products of group representations | Details will be provided during each class session. |
Class 7 | Induced representations | Details will be provided during each class session. |
Class 8 | Frobenius reciprocity | Details will be provided during each class session. |
Toshiyuki Katsura, Algebra II: Modules over a ring, Toudaishuppan (Japanese)
Unspecified.
Judging from the performance level of the exercises given during the class.
None required.