Welcome to Math 202C in the Spring quarter of 2022. This course concludes the applied algebra graduate course sequence, the previous installments of which were taught by Professor Freddie Manners and Professor Steven Sam. The goal of the course will be to unite and extend the material you learned in 202A and 202B in a natural, pleasing, and useful way. We will focus on applications of the representation theory of the symmetric groups, which was the subject of 202B. The Jucys-Murphy elements will be constructed, and their action in irreducible representations will be applied to analyze random walks (card shuffling) and permutation factorizations (Hurwitz theory). We then review some 202A material, namely the basic constructions of multilinear algebra (tensor, exterior, and symmetric algebras), and their physical interpretation as state spaces for bosons and fermions (Fock spaces). We apply the representation theory of the symmetric groups to prove the existence of a -Fock space interpolating between the symmetric and exterior algebras. The two parts of the course are then unified using the infinite wedge space formalism, whose connection with the theory of integrable systems via the Sato Grassmannian will be discussed if time permits.

Now to the mechanics of Math 202C. This post, Lecture 0, serves as the course syllabus. The course is being taught remotely, and the plan is that the two weekly lectures will be delivered in the form of blog posts like the one you are reading right now. Each of these posts will likely cover more than I would be able to cover in an in-person ninety minute lecture. These posts will appear every Tuesday and Thursday in a temporal neighborhood of our scheduled lecture slots, and the course will feel much like a reading course, albeit a fairly intense one leading up to a qualifying exam. I will also hold live office hours over Zoom, so that we can discuss the course content in real time, and so that I can embellish and add to it verbally. This will happen on Fridays, and we will work out a time over Piazza, which we will use as a question and answer forum (signup link here). We’ll be conducting all class-related discussion on Piazza. The quicker you begin asking questions on Piazza (rather than via emails), the quicker you’ll benefit from the collective knowledge of your classmates and instructors. I encourage you to ask questions when you’re struggling to understand a concept.

As for evaluation, there are no exams (neither midterm nor final), though of course you’ll be taking the Applied Algebra qualifying exam mid-quarter. We will however have weekly problem sets which will be due on Sundays and submitted via Gradescope. More information about this will be posted on Piazza. These problem sets will help to cement the concepts you’ll be learning in the course, and will also give you an idea of the sorts of problems that are likely to appear on the qualifying exam. I believe this is everything you need to know to get started — see you on Piazza starting today, and in real time on Friday.

1 | Spectral theorem, flags and Grassmannians, minimax |

2 | Jucys’s theorem: unique factorization |

3 | Symmetric polynomials and JM elements |

4 | Murphy’s theorem: content eigenvalues |

5 | Top-to-random shuffle I |

6 | Top-to-random shuffle II |

7 | Basic category theory |

8 | Tensor product, tensor powers, tensor algebra |

9 | Symmetric and antisymmetric tensors, bosons and fermions |

10 | Polynomials and varieties |

11 | Grassmann varieties |

12 | Selfadjoint algebras I |

13 | Selfadjoint algebras II |

14 | Selfadjoint algebras III |

15 | Unitary representations I |

16 | Unitary representations II |

17 | Unitary representations III |

18 | Schur-Weyl duality I |

19 | Schur-Weyl duality II |

20 | Invariant theory |