
arXiv: 2303.16569
AbstractGiven an arbitrary Coxeter system and a non‐negative integer , the ‐Shi arrangement of is a subarrangement of the Coxeter hyperplane arrangement of . The classical Shi arrangement () was introduced in the case of affine Weyl groups by Shi to study Kazhdan–Lusztig cells for . As two key results, Shi showed that each region of the Shi arrangement contains exactly one element of minimal length in and that the union of their inverses form a convex subset of the Coxeter complex. The set of ‐low elements in were introduced to study the word problem of the corresponding Artin–Tits (braid) group and they turn out to produce automata to study the combinatorics of reduced words in . In this article, we generalize and extend Shi's results to any Coxeter system for any : (1) the set of minimal length elements of the regions in a ‐Shi arrangement is precisely the set of ‐low elements, settling a conjecture of the first and third authors in this case; (2) the union of the inverses of the (0‐)low elements form a convex subset in the Coxeter complex, settling a conjecture by the third author, Nadeau and Williams.
Reflection and Coxeter groups (group-theoretic aspects), Reflection groups, reflection geometries, FOS: Mathematics, Mathematics - Combinatorics, Combinatorics (math.CO), Group Theory (math.GR), Root systems, Mathematics - Group Theory, Primary 20F55, 05E16, secondary 17B22, 06A07, 06A11, Combinatorial aspects of groups and algebras
Reflection and Coxeter groups (group-theoretic aspects), Reflection groups, reflection geometries, FOS: Mathematics, Mathematics - Combinatorics, Combinatorics (math.CO), Group Theory (math.GR), Root systems, Mathematics - Group Theory, Primary 20F55, 05E16, secondary 17B22, 06A07, 06A11, Combinatorial aspects of groups and algebras
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 1 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Average | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
