Permutations with Kazhdan-Lusztig polynomial P_{id,w}(q) = 1 + q^h

Abstract

Using resolutions of singularities introduced by Cortez and a method for calculating Kazhdan-Lusztig polynomials due to Polo, we prove the conjecture of Billey and Braden characterizing permutations w with Kazhdan-Lusztig polynomial P_{id,w}(q)=1+q^h for some h.

arXiv comment30 pages, 8 figures. Main body is by Woo, appendix by Billey and Weed