scholarly journals A Divided Difference Operator

2013 ◽  
Vol DMTCS Proceedings vol. AS,... (Proceedings) ◽  
Author(s):  
Nicholas Teff
Keyword(s):  
Difference Operator ◽  
Divided Difference ◽  
Root Systems ◽  
Bruhat Order ◽  
Flag Variety ◽  
International Audience ◽  
Complete Flag ◽  
Special Case

International audience We construct a divided difference operator using GKM theory. This generalizes the classical divided difference operator for the cohomology of the complete flag variety. This construction proves a special case of a recent conjecture of Shareshian and Wachs. Our methods are entirely combinatorial and algebraic, and rely heavily on the combinatorics of root systems and Bruhat order.

scholarly journals 0-Hecke algebra actions on coinvariants and flags

2011 ◽  
Vol DMTCS Proceedings vol. AO,... (Proceedings) ◽  
Author(s):  
Jia Huang
Keyword(s):  
Generating Functions ◽  
Hecke Algebra ◽  
Flag Variety ◽  
Major Index ◽  
Inversion Number ◽  
International Audience ◽  
Descent Set ◽  
Complete Flag ◽  
Coinvariant Algebra

International audience By investigating the action of the 0-Hecke algebra on the coinvariant algebra and the complete flag variety, we interpret generating functions counting the permutations with fixed inverse descent set by their inversion number and major index. En étudiant l'action de l'algèbre de 0-Hecke sur l'algèbre coinvariante et la variété de drapeaux complète, nous interprétons les fonctions génératrices qui comptent les permutations avec un ensemble inverse de descentes fixé, selon leur nombre d'inversions et leur "major index''.

scholarly journals Bruhat interval polytopes

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
Emmanuel Tsukerman ◽  
Lauren Williams
Keyword(s):  
Coxeter Groups ◽  
Toda Lattice ◽  
Bruhat Order ◽  
Flag Variety ◽  
Toda Hierarchy ◽  
Dimension Formula ◽  
Sont Respectivement ◽  
International Audience ◽  
The Moment ◽  
The Relationship

International audience Let $u$ and $v$ be permutations on $n$ letters, with $u$ &le; $v$ in Bruhat order. A <i>Bruhat interval polytope</i> $Q_{u,v}$ is the convex hull of all permutation vectors $z=(z(1),z(2),...,z(n))$ with $u$ &le; $z$ &le; $v$. Note that when $u=e$ and $v=w_0$ are the shortest and longest elements of the symmetric group, $Q_{e,w_0}$ is the classical permutohedron. Bruhat interval polytopes were studied recently in the 2013 paper “The full Kostant-Toda hierarchy on the positive flag variety” by Kodama and the second author, in the context of the Toda lattice and the moment map on the flag variety. In this paper we study combinatorial aspects of Bruhat interval polytopes. For example, we give an inequality description and a dimension formula for Bruhat interval polytopes, and prove that every face of a Bruhat interval polytope is a Bruhat interval polytope. A key tool in the proof of the latter statement is a generalization of the well-known lifting property for Coxeter groups. Motivated by the relationship between the lifting property and $R$-polynomials, we also give a generalization of the standard recurrence for $R$-polynomials. Soient $u$ et $v$ des permutations sur $n$ lettres, avec, $u$ &le; $v$ dans l’ordre de Bruhat. Un <i>polytope d’intervalles de Bruhat</i> $Q_{u,v}$ est l’enveloppe convexe de tous les vecteurs de permutations $z=(z(1),z(2),...,z(n))$ avec $u$ &le; $z$ &le; $v$. Notons que lorsque $u=e$ et $v=w_0$ sont respectivement le plus court et le plus long élément du groupe symétrique, $Q_{e,w_0}$ est le permutoèdre classique. Les polytopes d’intervalles de Bruhat ont été étudiés récemment dans le papier de 2013 “The full Kostant-Toda hierarchy on the positive flag variety” par Kodama et le deuxième auteur, dans le contexte du treillis de Toda et la carte des moments sur la variété de drapeaux. Dans ce papier nous étudions des aspects combinatoires des polytopes d’intervalles de Bruhat. Par exemple, nous donnons une description par inégalités et une formule dimensionnelle pour les polytopes d’intervalles de Bruhat, et prouvons que chaque face d’un polytope d’intervalles de Bruhat est un polytope d’intervalles de Bruhat. Un outil essentiel dans la preuve de cette dernière affirmation est une généralisation de la célèbre propriété de lifting pour les groupes de Coxeter. Motivés par la relation entre la propriété de lifting et les $R$-polynômes, nous donnons aussi une généralisation de la récurrence standard pour les $R$-polynômes.

scholarly journals Constrained exchangeable partitions

2006 ◽  
Vol DMTCS Proceedings vol. AG,... (Proceedings) ◽  
Author(s):  
Alexander Gnedin
Keyword(s):  
Central Limit Theorem ◽  
Limit Theorem ◽  
Central Limit ◽  
Random Partitions ◽  
Type Representation ◽  
International Audience ◽  
De Finetti ◽  
Infinite Set ◽  
Special Case

International audience For a class of random partitions of an infinite set a de Finetti-type representation is derived, and in one special case a central limit theorem for the number of blocks is shown.

scholarly journals Stability Anomalies of Some Jacobian-Free Iterative Methods of High Order of Convergence

Axioms ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 51
Author(s):  
Alicia Cordero ◽  
Javier G. Maimó ◽  
Juan R. Torregrosa ◽  
María P. Vassileva
Keyword(s):  
Difference Operator ◽  
Divided Difference ◽  
Polynomial System ◽  
Nonlinear Problems ◽  
Coefficient Matrix ◽  
Test Problems ◽  
Stability Performance ◽  
Need To Evaluate ◽  
The Stability ◽  
Theoretical Results

In this manuscript, we design two classes of parametric iterative schemes to solve nonlinear problems that do not need to evaluate Jacobian matrices and need to solve three linear systems per iteration with the same divided difference operator as the coefficient matrix. The stability performance of the classes is analyzed on a quadratic polynomial system, and it is shown that for many values of the parameter, only convergence to the roots of the problem exists. Finally, we check the performance of these methods on some test problems to confirm the theoretical results.

scholarly journals A New Class of Iterative Processes for Solving Nonlinear Systems by Using One Divided Differences Operator

Mathematics ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 776 ◽  
Author(s):  
Alicia Cordero ◽  
Cristina Jordán ◽  
Esther Sanabria ◽  
Juan R. Torregrosa
Keyword(s):  
Nonlinear Systems ◽  
Boundary Problem ◽  
Fourth Order ◽  
Difference Operator ◽  
Divided Difference ◽  
Order Convergence ◽  
New Class ◽  
Numerical Tests ◽  
New Family ◽  
Theoretical Results

In this manuscript, a new family of Jacobian-free iterative methods for solving nonlinear systems is presented. The fourth-order convergence for all the elements of the class is established, proving, in addition, that one element of this family has order five. The proposed methods have four steps and, in all of them, the same divided difference operator appears. Numerical problems, including systems of academic interest and the system resulting from the discretization of the boundary problem described by Fisher’s equation, are shown to compare the performance of the proposed schemes with other known ones. The numerical tests are in concordance with the theoretical results.

scholarly journals Hardy-type inequalities for Dunkl operators with applications to many-particle Hardy inequalities

2020 ◽  
pp. 2050024 ◽  
Author(s):  
Andrei Velicu
Keyword(s):  
Hardy Inequality ◽  
Root Systems ◽  
Dunkl Operators ◽  
Hardy Inequalities ◽  
One Dimensional ◽  
Hardy Type Inequalities ◽  
Rellich Inequality ◽  
Nirenberg Inequality ◽  
Special Case ◽  
The Hardy Inequality

In this paper, we study various forms of the Hardy inequality for Dunkl operators, including the classical inequality, [Formula: see text] inequalities, an improved Hardy inequality, as well as the Rellich inequality and a special case of the Caffarelli–Kohn–Nirenberg inequality. As a consequence, one-dimensional many-particle Hardy inequalities for generalized root systems are proved, which in the particular case of root systems [Formula: see text] improve some well-known results.

scholarly journals Twisted gamma filtration and algebras with orthogonal involution

2014 ◽  
Vol 12 (3) ◽  
Author(s):  
Caroline Junkins
Keyword(s):  
Algebraic Group ◽  
Grothendieck Group ◽  
Linear Algebraic Group ◽  
Flag Variety ◽  
Flag Varieties ◽  
Torsion Element ◽  
Complete Flag ◽  
Gamma Filtration

AbstractFor the Grothendieck group of a split simple linear algebraic group, the twisted γ-filtration provides a useful tool for constructing torsion elements in -rings of twisted flag varieties. In this paper, we construct a non-trivial torsion element in the γ-ring of a complete flag variety twisted by means of a PGO-torsor. This generalizes the construction in the HSpin case previously obtained by Zainoulline.

Integrability, Fusion, and Duality in the Elliptic Ruijsenaars Model

1997 ◽  
Vol 12 (11) ◽  
pp. 751-761 ◽  
Author(s):  
Kazuhiro Hikami ◽  
Yasushi Komori
Keyword(s):  
Difference Operator ◽  
Hecke Algebra ◽  
Root Systems ◽  
Baxter Equation ◽  
Reflection Equation ◽  
Fusion Procedure ◽  
Affine Hecke Algebra ◽  
Difference Analog ◽  
Type D ◽  
Ruijsenaars Models

The generalized elliptic Ruijsenaars models, which are regarded as a difference analog of the Calogero–Sutherland–Moser models associated with the classical root systems are studied. The integrability and the duality using the fusion procedure of operator-valued solutions of the Yang–Baxter equation and the reflection equation are shown. In particular a new integrable difference operator of type-D is proposed. The trigonometric models are also considered in terms of the representation of the affine Hecke algebra.

scholarly journals On the monotone hook hafnian conjecture

2011 ◽  
Vol DMTCS Proceedings vol. AO,... (Proceedings) ◽  
Author(s):  
Mirkó Visontai
Keyword(s):  
Graph Polynomials ◽  
Real Roots ◽  
Threshold Graphs ◽  
Multivariate Generalization ◽  
International Audience ◽  
Special Case

International audience We investigate a conjecture of Haglund that asserts that certain graph polynomials have only real roots. We prove a multivariate generalization of this conjecture for the special case of threshold graphs. Nous étudions une conjecture de Haglund qui affirme que certaines polynômes des graphes ont uniquement des racines réelles. Nous prouvons une généralisation multivariée de cette conjecture pour le cas particulier des graphes à seuil.

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