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The symmetric group acts on polynomial differential forms on $mathbb{R}^{n}$ through its action by permuting the coordinates. In this paper the $S_{n}% $-invariants are shown to be freely generated by the elementary symmetric polynomials and their exterior derivatives. A basis of the alternants in the quotient of the ideal generated by the homogeneous invariants of positive degree is given. In addition, the highest bigraded degrees are given for the quotient. All of these results are consistent with predictions derived by Garsia and Romero from a recent conjecture of Zabrocki.
The symmetric difference of the $q$-binomial coefficients $F_{n,k}(q)={n+kbrack k}-q^{n}{n+k-2brack k-2}$ was introduced by Reiner and Stanton. They proved that $F_{n,k}(q)$ is symmetric and unimodal for $k geq 2$ and $n$ even by using the representa
We obtain a combinatorial formula related to the shear transformation for semi-invariants of binary forms, which implies the classical characterization of semi-invariants in terms of a differential operator. Then, we present a combinatorial proof of
Let $W$ be a finite irreducible real reflection group, which is a Coxeter group. We explicitly construct a basis for the module of differential 1-forms with logarithmic poles along the Coxeter arrangement by using a primitive derivation. As a consequ
The Hall ratio of a graph $G$ is the maximum value of $v(H) / alpha(H)$ taken over all non-null subgraphs $H$ of $G$. For any graph, the Hall ratio is a lower-bound on its fractional chromatic number. In this note, we present various constructions of
In the 90s a collection of Plethystic operators were introduced in [3], [7] and [8] to solve some Representation Theoretical problems arising from the Theory of Macdonald polynomials. This collection was enriched in the research that led to the resul