scholarly journals Degrees of Regular Sequences With a Symmetric Group Action

2019 ◽  
Vol 71 (03) ◽  
pp. 557-578
Author(s):  
Federico Galetto ◽  
Anthony Vito Geramita ◽  
David Louis Wehlau
Keyword(s):  
Symmetric Group ◽  
Polynomial Ring ◽  
Group Action ◽  
Homogeneous Polynomials ◽  
Regular Sequences

AbstractWe consider ideals in a polynomial ring that are generated by regular sequences of homogeneous polynomials and are stable under the action of the symmetric group permuting the variables. In previous work, we determined the possible isomorphism types for these ideals. Following up on that work, we now analyze the possible degrees of the elements in such regular sequences. For each case of our classification, we provide some criteria guaranteeing the existence of regular sequences in certain degrees.

scholarly journals A Hessenberg Generalization of the Garsia-Procesi Basis for the Cohomology Ring of Springer Varieties

10.37236/425 ◽  
2010 ◽  
Vol 17 (1) ◽  
Author(s):  
Aba Mbirika
Keyword(s):  
Symmetric Group ◽  
Polynomial Ring ◽  
Group Action ◽  
Cohomology Ring ◽  
Geometric Construction ◽  
Nilpotent Operator ◽  
Hessenberg Varieties ◽  
New Evidence ◽  
Springer Variety ◽  
Two Parameter

The Springer variety is the set of flags stabilized by a nilpotent operator. In 1976, T.A. Springer observed that this variety's cohomology ring carries a symmetric group action, and he offered a deep geometric construction of this action. Sixteen years later, Garsia and Procesi made Springer's work more transparent and accessible by presenting the cohomology ring as a graded quotient of a polynomial ring. They combinatorially describe an explicit basis for this quotient. The goal of this paper is to generalize their work. Our main result deepens their analysis of Springer varieties and extends it to a family of varieties called Hessenberg varieties, a two-parameter generalization of Springer varieties. Little is known about their cohomology. For the class of regular nilpotent Hessenberg varieties, we conjecture a quotient presentation for the cohomology ring and exhibit an explicit basis. Tantalizing new evidence supports our conjecture for a subclass of regular nilpotent varieties called Peterson varieties.

scholarly journals Domino tableaux, Schützenberger involution, and the symmetric group action

2000 ◽  
Vol 225 (1-3) ◽  
pp. 15-24 ◽  
Author(s):  
Arkady Berenstein ◽  
Anatol N. Kirillov
Keyword(s):  
Symmetric Group ◽  
Group Action ◽  
Domino Tableaux

scholarly journals The Symmetric Group Action on Rank-selected Posets of Injective Words

Order ◽  
2016 ◽  
Vol 35 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Christos A. Athanasiadis
Keyword(s):  
Symmetric Group ◽  
Group Action

scholarly journals Componentwise linear ideals

1999 ◽  
Vol 153 ◽  
pp. 141-153 ◽  
Author(s):  
Jürgen Herzog ◽  
Takayuki Hibi
Keyword(s):  
Simplicial Complex ◽  
Polynomial Ring ◽  
Betti Numbers ◽  
Monomial Ideals ◽  
Homogeneous Polynomials ◽  
Graded Betti Numbers ◽  
Linear Resolution ◽  
Alexander Dual ◽  
Componentwise Linear Ideals ◽  
The Ideal

AbstractA componentwise linear ideal is a graded ideal I of a polynomial ring such that, for each degree q, the ideal generated by all homogeneous polynomials of degree q belonging to I has a linear resolution. Examples of componentwise linear ideals include stable monomial ideals and Gotzmann ideals. The graded Betti numbers of a componentwise linear ideal can be determined by the graded Betti numbers of its components. Combinatorics on squarefree componentwise linear ideals will be especially studied. It turns out that the Stanley-Reisner ideal IΔ arising from a simplicial complex Δ is componentwise linear if and only if the Alexander dual of Δ is sequentially Cohen-Macaulay. This result generalizes the theorem by Eagon and Reiner which says that the Stanley-Reisner ideal of a simplicial complex has a linear resolution if and only if its Alexander dual is Cohen-Macaulay.

scholarly journals A Combinatorial Model for the Decomposition of Multivariate Polynomial Rings as $S_n$-Modules

10.37236/8935 ◽  
2020 ◽  
Vol 27 (3) ◽  
Author(s):  
Rosa Orellana ◽  
Michael Zabrocki
Keyword(s):  
Symmetric Group ◽  
Polynomial Ring ◽  
Polynomial Rings ◽  
Invariant Polynomials ◽  
Multivariate Polynomial ◽  
Generating Set ◽  
Combinatorial Model

We consider the symmetric group $S_n$-module of the polynomial ring with $m$ sets of $n$ commuting variables and $m'$ sets of $n$ anti-commuting variables and show that the multiplicity of an irreducible indexed by the partition $\lambda$ (a partition of $n$) is the number of multiset tableaux of shape $\lambda$ satisfying certain column and row strict conditions.  We also present a finite generating set for the ring of $S_n$ invariant polynomials of this ring. 

and Spaces

2017 ◽  
Author(s):  
Matt Clay ◽  
Dan Margalit
Keyword(s):  
Group Theory ◽  
Symmetric Group ◽  
Cayley Graph ◽  
Group Action ◽  
Metric Spaces ◽  
Geometric Group Theory ◽  
Geometric Object ◽  
Geometric Objects ◽  
Group Of Symmetries

This chapter discusses the notion of space, first by explaining what it means for a group to be a group of symmetries of a geometric object. This is the idea of group action, and some examples are given. The chapter proceeds by defining, for any group G, the Cayley graph of G and shows that the symmetric group of of this graph is precisely the group G. It then introduces metric spaces, which formalize the notion of a geometric object, and highlights numerous metric spaces that groups can act on. It also demonstrates that groups themselves are metric spaces; in other words, groups themselves can be thought of as geometric objects. The chapter concludes by using these ideas to frame the motivating questions of geometric group theory. Exercises relevant to each idea are included.

scholarly journals Tail Positive Words and Generalized Coinvariant Algebras

10.37236/6970 ◽  
2017 ◽  
Vol 24 (3) ◽  
Author(s):  
Brendon Rhoades ◽  
Andrew Timothy Wilson
Keyword(s):  
Symmetric Group ◽  
Polynomial Ring ◽  
Hecke Algebra ◽  
Macdonald Polynomials ◽  
Isomorphism Type ◽  
Monomial Basis ◽  
Combinatorial Properties ◽  
Algebraic Properties ◽  
Standard Monomial ◽  
Coinvariant Algebra

Let $n,k,$ and $r$ be nonnegative integers and let $S_n$ be the symmetric group. We introduce a quotient $R_{n,k,r}$ of the polynomial ring $\mathbb{Q}[x_1, \dots, x_n]$ in $n$ variables which carries the structure of a graded $S_n$-module.  When $r \ge n$ or $k = 0$ the quotient $R_{n,k,r}$ reduces to the classical coinvariant algebra $R_n$ attached to the symmetric group. Just as algebraic properties of $R_n$ are controlled by combinatorial properties of permutations in $S_n$, the algebra of $R_{n,k,r}$ is controlled by the combinatorics of objects called tail positive words. We calculate the standard monomial basis of $R_{n,k,r}$ and its graded $S_n$-isomorphism type. We also view $R_{n,k,r}$ as a module over the 0-Hecke algebra $H_n(0)$, prove that $R_{n,k,r}$ is a projective 0-Hecke module, and calculate its quasisymmetric and nonsymmetric 0-Hecke characteristics. We conjecture a relationship between our quotient $R_{n,k,r}$ and the delta operators of the theory of Macdonald polynomials.

Elimination from Homogeneous Polynomials Over a Polynomial Ring

1976 ◽  
Vol 28 (6) ◽  
pp. 1269-1276
Author(s):  
John G. Stevens
Keyword(s):  
Polynomial Ring ◽  
Homogeneous Polynomials ◽  
Fixed Ideal

Let Ω be a field and Γ a parameter. We designate the set of all polynomials homogeneous in (X) = (X1, … , Xn) with coefficients in Ω [Γ] by H Ω Γ[X] and write such polynomials as F, F(X), or F(X, Γ). The degree of a polynomial in H Ω Γ [X] shall mean the degree in (X). Let I = (F1 … , Fr) be a fixed ideal in H Ω Γ [X] generated by F1 … , Fr.

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