• Pavillon President-Kennedy, UQAM

• ARTA III : Advances in representation theory of algebras (2014)

• Mathematics in Marseille with Mark Haiman, Cédrik and François Bergeron

• Mathematics at the beach, Richard Stanley and Adriano Garsia (2003)

• Mathematics at a bar in Banff with Adriano Garsia and Nantel Bergeron

• Mountain mathematics with Francois and Nantel Bergeron, Jennifer Morse and Adriano Garsia

• Welcome to LaCIM!

• Welcome to LaCIM!

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• Gilbert Labelle and Christophe Reutenauer

• Welcome to LaCIM!

• Welcome to LaCIM!

• Welcome to LaCIM!

• Welcome to LaCIM!

• Welcome to LaCIM!

• Welcome to LaCIM!

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# Welcome to LaCIM

The LaCIM  (Laboratoire de Combinatoire et d’Informatique Mathématique) is a research center gathering researchers, postdoctoral fellows, as well as graduate and undergraduate students interested in

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# Seminars

### On invariant ideals of representation rings of semisimple groupsFriday, 24 February 2017, 13:30

Abstract : The talk is based on my joint work with Sanghoon Baek and Kirill Zainoulline, see arXiv:1612.07278. To any semisimple group $G$, one can associate its weight lattice $\Lambda$, the set of simple weight $\overline{\omega}_1, \ldots, \overline{\omega}_n$, and the Well group $W$ acting on $\Lambda$. One can consider the Laurent polynomial rings $\mathbb{Q}[\Lambda]$ and $\mathbb{Z}[\Lambda]$ (the monomial corresponding to $\lambda \in \Lambda$) will be denoted by $e^\lambda$ and the $augmented$ $orbit$ $polynomials$ $p_i = -|W\overline{\omega}_i|+\sum_{\lambda \in W\overline{\omega}_i} e^\lambda.$ These polynomials generate ideals $I \subset \mathbb{Z}[\Lambda]$ and $I_\mathbb{Q} \subset \mathbb{Q}[\Lambda].$ One can also consider the character lattice of the maximal torus of $G:$ $T^*\subset \Lambda$ and the corresponding Laurent polynomial subrings $\mathbb{Z}[T^*] \subset \mathbb{Z}[\Lambda]$ and $\mathbb{Q}[T^*] \subset \mathbb{Q}[\Lambda]$. If certain (not very strong in the case of $\mathbb{Q}$, and very strong in the case of $\mathbb{Z}$) conditions on $T^*$ and $\Lambda$ are satisfies, I will explain how to find the intersections $I\cap \mathbb{Z}[T^*]$ and $I_{\mathbb{Q}} \cap \mathbb{Q}[T^*]$.

Abstract : TBA