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Nancy Wallace

Publications and source records attributed to Nancy Wallace.

5 recordsLinked to original sources

Representations of the quasi-partition algebras

The quasi-partition algebras were introduced by Daugherty and the first author as centralizers of the symmetric group. In this article, we give a more general definition of these algebras and give a construction of their simple modules. In addition, we introduce two new algebras, we give linear bases and show that for specializations of their parameters, these new algebras are isomorphic to centralizer algebras. We provide a generalized Bratteli diagram that illustrates how the representation theory of the three algebras discussed in this paper are related. Moreover, we give combinatorial formulas for the dimensions of the simple modules of these algebras.

math.RT

Toward a Schurification of Parking Function Formulas via bijections with Young Tableaux

This paper contains a partial answer to the open problem 3.11 of \cite{[H2008]}. That is to find an explicit bijection on Schröder paths that inverts the statistics area and bounce. This paper started as an attempt to write the sum over $m$-Schröder paths with a fix number of diagonal steps into Schur functions in the variables $q$ and $t$. Some results have been generalized to parking functions, and some bijections were made with standard Young tableaux giving way to partial combinatorial formulas in the basis $s_μ(q,t)s_λ(X)$ for $\nabla(e_n)$ (respectively, $\nabla^m(e_n)$), when $μ$ and $λ$ are hooks (respectively, $μ$ is of length one). We also give an explicit algorithm that gives all the Schröder paths related to a Schur function $s_μ(q,t)$ when $μ$ is of length one. In a sense, it is a partial decomposition of Schröder paths into crystals.

math.CO

Explicit Combinatorial Formulas for Some Irreducible Characters of the $GL_k\times \mathbb{S}_n$-module of multivariate diagonal harmonics

We give an explicit combinatorial formula for some irreducible components of $GL_k\times \mathbb{S}_n$-modules of multivariate diagonal harmonics. To this end we introduce a new path combinatorial object $T_{n,s}$ allowing us to give the formula directly in terms of Schur functions. This paper also contains formulas written in terms of Schur functions in the $q$ and $t$ variables for special cases of $\nabla(e_n)$, $\nabla^r(e_n)$ and $Δ'_{e_k}(e_n)$. We also give an interpretation in term of path to the adjoint dual Pieri rule applied on these $GL_k\times \mathbb{S}_n$-characters.

math.CO

Nouvelles conditions pour l'inexistence des nombres parfaits impairs

We will show the two following results: If there existe an odd perfect number $n$ of prime decomposition $n=p_1^{α_1} \ldots p_k^{α_k}q^β$, where the $α_i$ are even, the $β$ are odd and $q \equiv 5 \mod 8$. Then there is at least one $p_i$, $1 \leq i \leq k$ that is not a square in $\mathbb{Z}/q\mathbb{Z}$. More precisely there is an odd number of $p_i$ that are not squares in $\mathbb{Z}/q\mathbb{Z}$. If there exist an odd perfect number $n$ of prime decomposition $n=p_1^{α_1} \ldots p_k^{α_k}q^β$, where the $α_i$ are even, the $β$ are odd and $p_{k+1} \equiv {1\mod 8}$. Then at least one $p_i$, $1 \leq i \leq k+1$ is a non zero square in at least one $\mathbb{Z}/{p_j}\mathbb{Z}$, $1 \leq j \leq k+1$. Contains an appendix of known results. ----- Un nombre, $n$, est dit parfait s'il est égal à la somme de ses diviseurs propres plus 1. Par exemple $6=1+2+3$. Dans ce document, les deux propositions suivantes seront démontrées: S'il existe un nombre parfait impair, $n$, de décomposition en nombre premier $n=p_1^{α_1} \ldots p_k^{α_k}q^β$, où les $ α_i$ sont pairs, $β$ est impair et $q \equiv 5 \mod 8$. Alors, au moins un $p_i$, $1 \leq i \leq k$ n'est pas un carré dans $\mathbb{Z}/q\mathbb{Z}$. Plus précisément un nombre impair de $p_i$ ne sont pas des carrés dans $\mathbb{Z}/q\mathbb{Z}$. S'il existe un nombre parfait impair, $n$, de décomposition en nombre premier $n=p_1^{α_1} \ldots p_k^{α_k}q^β$, où les $α_i$ sont pairs, $β$ est impair et $p_{k+1} \equiv {1\mod 8}$. Alors au moins un $p_i$, $1 \leq i \leq k+1$ est un carré non nul dans au moins un $\mathbb{Z} / {p_j}\mathbb{Z}$, $1 \leq j \leq k+1$. Contiens une annexe contenant les résultats déjà connus et des preuves que j'en ai faites.

math.HO

Les chemins de Schröder

Après avoir posé les définitions nécessaires à la compréhension du sujet, nous discuterons de statistique d'inversion diagonale dans les $r$-Schröder, de chemins de stationnement dans les $r$-Schröder à pente entière et nous développerons une formule pour les chemins de Schröder ayant une fraction unitaire comme pente. After setting the definitions we discuss of diagonal inversions on $r$-Shröder paths, of parking fonctions on $r$-Shröder paths with an integer slope and we develop a formula for Shröder paths with a $1/r$ slope, with $r$ an integer.

math.CO