scholarly journals Rigidity for the Hopf Algebra of Quasisymmetric Functions

10.37236/8174 ◽  
2019 ◽  
Vol 26 (3) ◽  
Author(s):  
Wanwan Jia ◽  
Zhengpan Wang ◽  
Houyi Yu
Keyword(s):  
Hopf Algebra ◽  
Graded Algebra ◽  
Quasisymmetric Functions ◽  
Monomial Basis ◽  
Combinatorial Properties ◽  
Linear Maps ◽  
Pieri Rules ◽  
Graded Coalgebra

We investigate the rigidity for the Hopf algebra QSym of quasisymmetric functions with respect to the monomial, the fundamental and the quasisymmetric Schur basis, respectively. By establishing some combinatorial properties of the posets of compositions arising from the analogous Pieri rules for quasisymmetric functions, we show that QSym is rigid as an algebra with respect to the quasisymmetric Schur basis, and rigid as a coalgebra with respect to the monomial and the quasisymmetric Schur basis, respectively. The natural actions of reversal, complement and transpose of the labelling compositions lead to some nontrivial graded (co)algebra automorphisms of QSym. We prove that the linear maps induced by the three actions are precisely the only nontrivial graded algebra automorphisms that take the fundamental basis into itself. Furthermore, the complement map on the labels gives the unique nontrivial graded coalgebra automorphism preserving the fundamental basis, while the reversal map on the labels gives the unique nontrivial graded algebra automorphism preserving the monomial basis. Therefore, QSym is rigid as a Hopf algebra with respect to the monomial and the quasisymmetric Schur basis.

scholarly journals Colored Trees and Noncommutative Symmetric Functions

10.37236/468 ◽  
2010 ◽  
Vol 17 (1) ◽  
Author(s):  
Matt Szczesny
Keyword(s):  
Hopf Algebra ◽  
Symmetric Functions ◽  
Hall Algebra ◽  
Quasisymmetric Functions ◽  
Noncommutative Symmetric Functions

Let ${\cal CRF}_S$ denote the category of $S$-colored rooted forests, and H$_{{\cal CRF}_S}$ denote its Ringel-Hall algebra as introduced by Kremnizer and Szczesny. We construct a homomorphism from a $K^+_0({\cal CRF}_S)$–graded version of the Hopf algebra of noncommutative symmetric functions to H$_{{\cal CRF}_S}$. Dualizing, we obtain a homomorphism from the Connes-Kreimer Hopf algebra to a $K^+_0({\cal CRF}_S)$–graded version of the algebra of quasisymmetric functions. This homomorphism is a refinement of one considered by W. Zhao.

scholarly journals Antipode Formulas for some Combinatorial Hopf Algebras

10.37236/5949 ◽  
2016 ◽  
Vol 23 (4) ◽  
Author(s):  
Rebecca Patrias
Keyword(s):  
Hopf Algebra ◽  
Hopf Algebras ◽  
Symmetric Functions ◽  
Explicit Formulas ◽  
Quasisymmetric Functions ◽  
Noncommutative Symmetric Functions ◽  
Combinatorial Hopf Algebras ◽  
Combinatorial Formulas ◽  
K Theory

Motivated by work of Buch on set-valued tableaux in relation to the K-theory of the Grassmannian, Lam and Pylyavskyy studied six combinatorial Hopf algebras that can be thought of as K-theoretic analogues of the Hopf algebras of symmetric functions, quasisymmetric functions, noncommutative symmetric functions, and of the Malvenuto-Reutenauer Hopf algebra of permutations. They described the bialgebra structure in all cases that were not yet known but left open the question of finding explicit formulas for the antipode maps. We give combinatorial formulas for the antipode map for the K-theoretic analogues of the symmetric functions, quasisymmetric functions, and noncommutative symmetric functions.

scholarly journals Hopf algebra structure of symmetric and quasisymmetric functions in superspace

2019 ◽  
Vol 166 ◽  
pp. 144-170
Author(s):  
Susanna Fishel ◽  
Luc Lapointe ◽  
María Elena Pinto
Keyword(s):  
Hopf Algebra ◽  
Algebra Structure ◽  
Quasisymmetric Functions ◽  
Hopf Algebra Structure

scholarly journals Racks, Leibniz algebras and Yetter–Drinfel'd modules

2015 ◽  
Vol 22 (4) ◽  
Author(s):  
Ulrich Krähmer ◽  
Friedrich Wagemann
Keyword(s):  
Hopf Algebra ◽  
Leibniz Algebra ◽  
Unified Framework ◽  
Leibniz Algebras ◽  
Linear Maps

AbstractA Hopf algebra object in Loday and Pirashvili's category of linear maps entails an ordinary Hopf algebra and a Yetter–Drinfel'd module. We equip the latter with a structure of a braided Leibniz algebra. This provides a unified framework for examples of racks in the category of coalgebras discussed recently by Carter, Crans, Elhamdadi and Saito.

scholarly journals The monomial basis and the $$Q$$ Q -basis of the Hopf algebra of parking functions

2015 ◽  
Vol 42 (2) ◽  
pp. 473-496 ◽  
Author(s):  
Teresa Xueshan Li
Keyword(s):  
Hopf Algebra ◽  
Parking Functions ◽  
Monomial Basis

scholarly journals Free polynomial generators for the Hopf algebra QSym of quasisymmetric functions

1999 ◽  
Vol 144 (3) ◽  
pp. 213-227 ◽  
Author(s):  
E.J. Ditters ◽  
A.C.J. Scholtens
Keyword(s):  
Hopf Algebra ◽  
Quasisymmetric Functions

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.

scholarly journals TWISTING ALL THE WAY: FROM ALGEBRAS TO MORPHISMS AND CONNECTIONS

2012 ◽  
Vol 13 ◽  
pp. 1-19 ◽  
Author(s):  
PAOLO ASCHIERI
Keyword(s):  
Hopf Algebra ◽  
Tensor Product ◽  
Commutative Algebra ◽  
Tensor Products ◽  
Module Algebra ◽  
Linear Maps ◽  
Definition Of ◽  
Quasitriangular Hopf Algebra ◽  
Just Right ◽  
The Way

Given a Hopf algebra H and an algebra A that is an H-module algebra we consider the category of left H-modules and A-bimodules [Formula: see text], where morphisms are just right A-linear maps (not necessarily H-equivariant). Given a twist [Formula: see text] of H we then quantize (deform) H to [Formula: see text], A to A⋆ and correspondingly the category [Formula: see text] to [Formula: see text]. If we consider a quasitriangular Hopf algebra H, a quasi-commutative algebra A and quasi-commutative A-bimodules, we can further construct and study tensor products over A of modules and of morphisms, and their twist quantization. This study leads to the definition of arbitrary (i.e., not necessarily H-equivariant) connections on quasi-commutative A-bimodules, to extend these connections to tensor product modules and to quantize them to A⋆-bimodule connections. Their curvatures and those on tensor product modules are also determined.

scholarly journals Integer points enumerator of hypergraphic polytopes

2021 ◽  
pp. 1-1
Author(s):  
Marko Pesovic
Keyword(s):  
Positive Integer ◽  
Hopf Algebra ◽  
Symmetric Function ◽  
Quasisymmetric Function ◽  
Quasisymmetric Functions ◽  
Simple Graphs ◽  
Integer Points ◽  
Combinatorial Hopf Algebra ◽  
Chromatic Symmetric Function

For a hypergraphic polytope there is a weighted quasisymmetric function which enumerates positive integer points in its normal fan and determines its f-polynomial. This quasisymmetric function invariant of hypergraphs extends the Stanley chromatic symmetric function of simple graphs. We consider a certain combinatorial Hopf algebra of hypergraphs and show that universal morphism to quasisymmetric functions coincides with this enumerator function. We calculate the f-polynomial of uniform hypergraphic polytopes.

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