Sorting orders, subword complexes, Bruhat order and total positivity
Abstract
In this note we construct a poset map from a Boolean algebra to the Bruhat order which unveils an interesting connection between subword complexes, sorting orders, and certain totally nonnegative spaces. This relationship gives a new proof of Bj\"orner and Wachs' result \cite{BW} that the proper part of Bruhat order is homotopy equivalent to the proper part of a Boolean algebra --- that is, to a sphere. We also obtain a geometric interpretation for sorting orders. We conclude with two new results: that the intersection of all sorting orders is the weak order, and the union of sorting orders is the Bruhat order.
Cite
@article{arxiv.0909.2828,
title = {Sorting orders, subword complexes, Bruhat order and total positivity},
author = {Drew Armstrong and Patricia Hersh},
journal= {arXiv preprint arXiv:0909.2828},
year = {2010}
}
Comments
10 pages, 1 figure. This is the official version. It is more official than the version that appears in Advances in Applied Mathematics