Tag - Combinatorial representation theory

Oleksandr Tsymbaliuk: Lyndon words and fused currents in shuffle algebra

2nd March, 2024

Classical q-shuffle algebras provide combinatorial models for the positive half Uq(𝔫) of a finite quantum group. We define a loop version of this construction, yielding a combinatorial model for the positive half Uq(L𝔫) of a quantum loop group. In particular, we construct a PBW basis of Uq(L𝔫) indexed by standard Lyndon words, generalizing the work of Lalonde-Ram, Leclerc and Rosso in the Uq(𝔫) case. We also connect this to Enriquez's degeneration A of the elliptic algebras of Feigin-Odesskii, proving a conjecture that describes the image of the embedding Uq(L𝔫)→A in terms of pole and wheel conditions. The talk shall conclude with the shuffle interpretations of fused currents proposed by Ding-Khoroshkin.

Travis Scrimshaw: An Overview of Kirillov-Reshtikhin Modules and Crystals

19th January, 2024

Kirillov-Reshetikhin (KR) modules are an important class of finite-dimensional representations associated to an affine Lie algebra and the associated Yangian and quantum group. KR modules are known to appear in many integrable systems and govern the dynamics. In this talk, we will give an overview of the role KR modules play in the category of finite-dimensional representations, R-matrices and the fusion construction, their (conjectural) crystal bases, and how they relate to Demazure modules. In particular, we will focus on how to construct their crystal bases combinatorially and the different types of character theories. As time permits, we will discuss some of the relations with (quantum) integrable systems.