Artin group injection in the Hecke algebra for right-angled groups

For any Coxeter system we consider the algebra generated by the projections over the parabolic quotients. In the finite case it turn out that this algebra is isomorphic to the monoid algebra of the Coxeter monoid (0-Hecke algebra). In the infinite case it contains the Coxeter monoid algebra as a proper subalgebra. This construction provides a faithful integral representation of the Coxeter monoid algebra of any Coxeter system. As an application we will prove that a right-angled Artin group injects in Hecke algebra of the corresponding right-angled Coxeter group

The generalized lifting property of Bruhat intervlas

In [E. Tsukerman and L. Williams, {\em Bruhat Interval Polytopes}, Advances in Mathematics, 285 (2015), 766-810] it is shown that every Bruhat interval of the symmetric group satisfies the so-called generalized lifting property. In this paper we show that a Coxeter group satisfies this property if and only if it is finite and simply-laced.Comment: 18 page

Parabolically induced functions and equidistributed pairs

Given a function defined over a parabolic subgroup of a Coxeter group, equidistributed with the length, we give a procedure to construct a function over the entire group, equidistributed with the length. Such a procedure permits to define functions equidistributed with the length in all the finite Coxeter groups. We can establish our results in the general setting of graded posets which satisfy some properties. These results apply to some known functions arising in Coxeter groups as the major index, the negative major index and the D-negative major index defined in type $A$, $B$ and $D$ respectively

Immanant varieties

We introduce immanant varieties, associated to simple characters of a finite group. They include well studied classes of varieties, as Segre embeddings, Grassmannians and some other Chow varieties. For a one-dimensional character $\chi$, we define $\chi$-matroids by a maximality property. For trivial characters, by exploring the combinatorics of incidence stratifications, we provide a basis for the Chow vector spaces of the corresponding immanant varieties

Wachs permutations, Bruhat order and weak order

We study the partial orders induced on Wachs and signed Wachs permutations by the Bruhat and weak orders of the symmetric and hyperoctahedral groups. We show that these orders are graded, determine their rank function, characterize their ordering and covering relations, and compute their characteristic polynomials, when partially ordered by Bruhat order, and determine their structure explicitly when partially ordered by right weak order

Linear extensions and shelling orders

We prove that linear extensions of the Bruhat order of a matroid are shelling orders and that the barycentric subdivision of a matroid is a Coxeter matroid, viewing barycentric subdivisions as subsets of a parabolic quotient of a symmetric group. A similar result holds for order ideals in minuscule quotients of symmetric groups and in their barycentric subdivisions. Moreover, we apply promotion and evacuation for labeled graphs of Malvenuto and Reutenauer to dual graphs of simplicial complexes, providing promotion and evacuation of shelling orders

pp-Jones-Wenzl idempotents

For a prime number $p$ and any natural number $n$ we introduce, by giving an explicit recursive formula, the $p$-Jones-Wenzl projector ${}^p\operatorname{JW}_n$, an element of the Temperley-Lieb algebra $TL_n(2)$ with coefficients in ${\mathbb F}_p$. We prove that these projectors give the indecomposable objects in the $\tilde{A}_1$-Hecke category over ${\mathbb F}_p$, or equivalently, they give the projector in $\mathrm{End}_{\mathrm{SL}_2(\overline{{\mathbb F}_p})}(({\mathbb F}_p^2)^{\otimes n})$ to the top tilting module. The way in which we find these projectors is by categorifying the fractal appearing in the expression of the $p$-canonical basis in terms of the Kazhdan-Lusztig basis for $\tilde{A}_1$.Comment: 15 pages, 21 figures. Many minor changes. Major change of notation. Final versio

The generalized lifting property of Bruhat intervals

In Tsukerman and Williams (Adv Math 285: 766\u2013810, 2015), it is shown that every Bruhat interval of the symmetric group satisfies the so-called generalized lifting property. In this paper, we show that a Coxeter group satisfies this property if and only if it is finite and simply-laced