Fermionic Formulas for Weight Multiplicities
We assume a working knowledge of linear algebra and vector spaces, including basic definitions and theorems. Familiarity with elementary facts from algebraic geometry and integrable systems is also expected.
Lecturer
Anatoli Kirillov
Date
3rd March ~ 29th May, 2026
Location
| Weekday | Time | Venue | Online | ID | Password |
|---|---|---|---|---|---|
| Tuesday | 13:30 - 15:05 | A3-1a-205 | ZOOM 04 | 482 240 1589 | BIMSA |
| Friday | 15:20 - 16:55 | A3-1a-205 | ZOOM 04 | 482 240 1589 | BIMSA |
Syllabus
Part I. Refreshment
Lectures 1-6
Lie groups and Lie algebras.
Main examples: symmetric and general linear groups; definitions and basic properties.
(Overview) Representation theory of symmetric and general linear groups: Schur functions, Cauchy identities, Schur-Weyl duality, and Howe duality.
Part II. Combinatorics
Lectures 7-15
Compositions (strong and weak).
Diagrams of partitions; Young tableaux (strong or strict semi-simple; column/rowstrict tableaux).
Symmetric functions and (semi-simple) Young tableaux.
Symmetric functions and characters of finite-dimensional irreducible representations of the symmetric and general linear groups.
Dimension formulas for characters.
Kostant partition functions; Kostka numbers and polynomials.
Weight multiplicities, Littlewood-Richardson rule, and Robinson-Schensted correspondence.
Part III. Fermionic Formulas for Parabolic Kostka Polynomials
Lectures 18-21
Overview of the Bethe Ansatz (BA) and Bethe Ansatz equations (BAE) for the (generalized) Heisenberg spin chain.
Combinatorial analysis of BAE: string conjectures and vacancy numbers.
Rigged configurations; special matrices and riggings.
Initial data: \((\lambda, R)\), where \(\lambda \vdash n\) is a partition, and \(R = \{(\mu_a^{n_a})\}_{a \geq 1}\) is a set of rectangular-shape partitions such that \(\sum_{a \geq 1} \mu_a n_a = n\).
Special matrices \(\{m_{ij} \in \mathbb{Z} \mid 1 \leq i, j \leq n\}\) (note that, in general, \(m_{ij}\) may be negative integers).
Framing (or riggings) of special matrices, given by explicit formulas using the set of rectangles \(R\).
Charge of a framing configuration and the polynomial associated with a given framed matrix \(\{m_{ij}\}\).
Parabolic Kostka polynomials \(K_{\lambda,R}(q)\), where \(\lambda \vdash n\), \(R = \{\mu_a^{n_a}\}_{a \geq 1}\), and \(\mu_1 \geq \mu_2 \geq \dots\).
**Main Theorem**: The parabolic Kostka polynomial \(K_{\lambda,R}(q)\) is equal to the sum of charged framed (or rigged) special matrices of type \((\lambda, R)\).
Part IV. Rigged Configuration Bijection
Bijection between framed special matrices and the corresponding Littlewood-Richardson tableaux.
Lectures 1-6
Lie groups and Lie algebras.
Main examples: symmetric and general linear groups; definitions and basic properties.
(Overview) Representation theory of symmetric and general linear groups: Schur functions, Cauchy identities, Schur-Weyl duality, and Howe duality.
Part II. Combinatorics
Lectures 7-15
Compositions (strong and weak).
Diagrams of partitions; Young tableaux (strong or strict semi-simple; column/rowstrict tableaux).
Symmetric functions and (semi-simple) Young tableaux.
Symmetric functions and characters of finite-dimensional irreducible representations of the symmetric and general linear groups.
Dimension formulas for characters.
Kostant partition functions; Kostka numbers and polynomials.
Weight multiplicities, Littlewood-Richardson rule, and Robinson-Schensted correspondence.
Part III. Fermionic Formulas for Parabolic Kostka Polynomials
Lectures 18-21
Overview of the Bethe Ansatz (BA) and Bethe Ansatz equations (BAE) for the (generalized) Heisenberg spin chain.
Combinatorial analysis of BAE: string conjectures and vacancy numbers.
Rigged configurations; special matrices and riggings.
Initial data: \((\lambda, R)\), where \(\lambda \vdash n\) is a partition, and \(R = \{(\mu_a^{n_a})\}_{a \geq 1}\) is a set of rectangular-shape partitions such that \(\sum_{a \geq 1} \mu_a n_a = n\).
Special matrices \(\{m_{ij} \in \mathbb{Z} \mid 1 \leq i, j \leq n\}\) (note that, in general, \(m_{ij}\) may be negative integers).
Framing (or riggings) of special matrices, given by explicit formulas using the set of rectangles \(R\).
Charge of a framing configuration and the polynomial associated with a given framed matrix \(\{m_{ij}\}\).
Parabolic Kostka polynomials \(K_{\lambda,R}(q)\), where \(\lambda \vdash n\), \(R = \{\mu_a^{n_a}\}_{a \geq 1}\), and \(\mu_1 \geq \mu_2 \geq \dots\).
**Main Theorem**: The parabolic Kostka polynomial \(K_{\lambda,R}(q)\) is equal to the sum of charged framed (or rigged) special matrices of type \((\lambda, R)\).
Part IV. Rigged Configuration Bijection
Bijection between framed special matrices and the corresponding Littlewood-Richardson tableaux.
Reference
[1] Berenstein, A. D., and Kirillov, A. N. (2016). Cactus group and Gelfand-Tsetlin group. Res. Inst. Math. Sci. preprint RIMS-1858.
[2] Macdonald, I. G. (1998). Symmetric functions and Hall polynomials. Oxford University Press.
[3] Kirillov, A. N. (2001). Combinatorics of Young tableaux and configurations. Proceedings of the St. Petersburg Mathematical Society Volume VII, 203, 17-98.
[4] Kirillov, A. N. (2015). Rigged Configurations and Catalan, Stretched Parabolic Kostka Numbers and Polynomials: Polynomiality, Unimodality and Logconcavity. arXiv preprint arXiv:1505.01542.
[5] Kirillov, A. N., et al. (2016). On some quadratic algebras I 1/2: Combinatorics of Dunkl and Gaudin elements, Schubert, Grothendieck, Fuss-Catalan, universal Tutte and reduced polynomials. SIGMA. Symmetry, Integrability and Geometry: Methods and Applications, 12, 002.
[6] Kirillov, A. N. (2021). Rigged Configurations and Unimodality. In Representation Theory, Mathematical Physics, and Integrable Systems: In Honor of Nicolai Reshetikhin (pp. 453-496). Springer.
[2] Macdonald, I. G. (1998). Symmetric functions and Hall polynomials. Oxford University Press.
[3] Kirillov, A. N. (2001). Combinatorics of Young tableaux and configurations. Proceedings of the St. Petersburg Mathematical Society Volume VII, 203, 17-98.
[4] Kirillov, A. N. (2015). Rigged Configurations and Catalan, Stretched Parabolic Kostka Numbers and Polynomials: Polynomiality, Unimodality and Logconcavity. arXiv preprint arXiv:1505.01542.
[5] Kirillov, A. N., et al. (2016). On some quadratic algebras I 1/2: Combinatorics of Dunkl and Gaudin elements, Schubert, Grothendieck, Fuss-Catalan, universal Tutte and reduced polynomials. SIGMA. Symmetry, Integrability and Geometry: Methods and Applications, 12, 002.
[6] Kirillov, A. N. (2021). Rigged Configurations and Unimodality. In Representation Theory, Mathematical Physics, and Integrable Systems: In Honor of Nicolai Reshetikhin (pp. 453-496). Springer.
Video Public
Yes
Notes Public
Yes
Language
English
Lecturer Intro
Anatol Kirillov is a researcher in the area of integrable systems, representation theory, special functions, algebraic combinatorics, and algebraic geometry. He worked as a professor in different universities in Japan for the last 20 years. In 2022 he joined BIMSA as a research fellow.