scholarly journals Visibility graphs of staircase polygons and the weak Bruhat order, I: From visibility graphs to maximal chains

1995 ◽  
Vol 14 (3) ◽  
pp. 331-358 ◽  
Author(s):  
J. Abello ◽  
O. Egecioglu ◽  
K. Kumar
Keyword(s):  
Bruhat Order ◽  
Visibility Graphs ◽  
Weak Bruhat Order ◽  
Maximal Chains

scholarly journals Higher Bruhat Orders in Type B

10.37236/5620 ◽  
2016 ◽  
Vol 23 (3) ◽  
Author(s):  
Seth Shelley-Abrahamson ◽  
Suhas Vijaykumar
Keyword(s):  
Symmetric Group ◽  
Minimal Element ◽  
Partially Ordered Sets ◽  
Bruhat Order ◽  
Hyperplane Arrangements ◽  
Type B ◽  
Ordered Sets ◽  
Weak Bruhat Order ◽  
Positive Integers ◽  
Maximal Chains

Motivated by the geometry of hyperplane arrangements, Manin and Schechtman defined for each integer $n \geq 1$ a hierarchy of finite partially ordered sets $B(n, k),$ indexed by positive integers $k$, called the higher Bruhat orders.  The poset $B(n, 1)$ is naturally identified with the weak left Bruhat order on the symmetric group $S_n$, each $B(n, k)$ has a unique maximal and a unique minimal element, and the poset $B(n, k + 1)$ can be constructed from the set of maximal chains in $B(n, k)$.  Ben Elias has demonstrated a striking connection between the posets $B(n, k)$ for $k = 2$ and the diagrammatics of Bott-Samelson bimodules in type A, providing significant motivation for the development of an analogous theory of higher Bruhat orders in other Cartan-Killing types, particularly for $k = 2$.  In this paper we present a partial generalization to type B, complete up to $k = 2$, prove a direct analogue of the main theorem of Manin and Schechtman, and relate our construction to the weak Bruhat order and reduced expression graph for Weyl group $B_n$.

scholarly journals The Skeleton of a Reduced Word and a Correspondence of Edelman and Greene

10.37236/1554 ◽  
2000 ◽  
Vol 8 (1) ◽  
Author(s):  
Stefan Felsner
Keyword(s):  
Bruhat Order ◽  
Young Tableaux ◽  
Reduced Word ◽  
Reduced Decompositions ◽  
Bijective Proof ◽  
Identity Permutation ◽  
Weak Bruhat Order ◽  
Classical Correspondence ◽  
Standard Young Tableaux ◽  
Maximal Chains

Stanley conjectured that the number of maximal chains in the weak Bruhat order of $S_n$, or equivalently the number of reduced decompositions of the reverse of the identity permutation $ w_0 = n,n-1,n-2,\ldots,2,1$, equals the number of standard Young tableaux of staircase shape $s=\{n-1,n-2,\ldots,1\}$. Originating from this conjecture remarkable connections between standard Young tableaux and reduced words have been discovered. Stanley proved his conjecture algebraically, later Edelman and Greene found a bijective proof. We provide an extension of the Edelman and Greene bijection to a larger class of words. This extension is similar to the extension of the Robinson-Schensted correspondence to two line arrays. Our proof is inspired by Viennot's planarized proof of the Robinson-Schensted correspondence. As it is the case with the classical correspondence the planarized proofs have their own beauty and simplicity.

scholarly journals Alignments, crossings, cycles, inversions, and weak Bruhat order in permutation tableaux of type $B$

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
Soojin Cho ◽  
Kyoungsuk Park
Keyword(s):  
Bruhat Order ◽  
Type B ◽  
Coxeter System ◽  
Covering Relation ◽  
Signed Permutations ◽  
Weak Bruhat Order ◽  
International Audience

International audience Alignments, crossings and inversions of signed permutations are realized in the corresponding permutation tableaux of type $B$, and the cycles of signed permutations are understood in the corresponding bare tableaux of type $B$. We find the relation between the number of alignments, crossings and other statistics of signed permutations, and also characterize the covering relation in weak Bruhat order on Coxeter system of type $B$ in terms of permutation tableaux of type $B$. De nombreuses statistiques importantes des permutations signées sont réalisées dans les tableaux de permutations ou ”bare” tableaux de type $B$ correspondants : les alignements, croisements et inversions des permutations signées sont réalisés dans les tableaux de permutations de type $B$ correspondants, et les cycles des permutations signées sont comprises dans les ”bare” tableaux de type $B$ correspondants. Cela nous mène à relier le nombre d’alignements et de croisements avec d’autres statistiques des permutations signées, et aussi de caractériser la relation de couverture dans l’ordre de Bruhat faible sur des systèmes de Coxeter de type $B$ en termes de tableaux de permutations de type $B$.

scholarly journals Local finiteness of the twisted Bruhat orders on affine Weyl groups

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Weijia Wang
Keyword(s):  
Root System ◽  
Coxeter Group ◽  
Bruhat Order ◽  
Weyl Groups ◽  
Oriented Matroid ◽  
Positive System ◽  
Locally Finite ◽  
Affine Weyl Groups ◽  
Affine Weyl Group ◽  
Weak Bruhat Order

AbstractIn this paper, we investigate various properties of strong and weak twisted Bruhat orders on a Coxeter group. In particular, we prove that any twisted strong Bruhat order on an affine Weyl group is locally finite, strengthening a result of Dyer [Quotients of twisted Bruhat orders, J. Algebra163 (1994), 3, 861–879]. We also show that, for a non-finite and non-cofinite biclosed set 𝐵 in the positive system of an affine root system with rank greater than 2, the set of elements having a fixed 𝐵-twisted length is infinite. This implies that the twisted strong and weak Bruhat orders have an infinite antichain in those cases. Finally, we show that twisted weak Bruhat order can be applied to the study of the tope poset of an infinite oriented matroid arising from an affine root system.

scholarly journals From the weak Bruhat order to crystal posets

2016 ◽  
Vol 286 (3-4) ◽  
pp. 1435-1464 ◽  
Author(s):  
Patricia Hersh ◽  
Cristian Lenart
Keyword(s):  
Bruhat Order ◽  
Weak Bruhat Order
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