Séminaire Lotharingien de Combinatoire, 91B.67 (2024), 12 pp.

Nantel Bergeron and Lucas Gagnon

Excedance quotients, Quasisymmetric Varieties, and Temperley-Lieb algebras

Abstract. Let Rn = Q[x1,x2,...,xn] be the ring of polynomials in n variables and consider the ideal < QSymn+ > ⊆ Rn generated by quasisymmetric polynomials without constant term. It was shown by Aval, Bergeron and Bergeron that dim(Rn / < QSymn+ >) = Cn the nth Catalan number. We explain here this phenomenon by defining a set of permutations QSVn with the following properties: first, QSVn is a basis of the Temperley-Lieb algebra TLn(2), and second, when considering QSVn as a collection of points in Qn, the top-degree homogeneous component of the vanishing ideal I(QSVn) is < QSymn+ >. Our construction has a few byproducts which are independently noteworthy.


Received: November 15, 2023. Accepted: February 15, 2024. Final version: April 1, 2024.

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