Explicit Enumeration of 321,Hexagon-Avoiding Permutations
| dc.creator | Stankova-Frenkel, Zvezdelina | |
| dc.creator | West, Julian | |
| dc.date | 2001-06-11 | |
| dc.date.accessioned | 2026-07-07T04:42:05Z | |
| dc.date.available | 2026-07-07T04:42:05Z | |
| dc.description | The 321,hexagon-avoiding (321-hex) permutations were introduced and studied by Billey and Warrington in as a class of elements of S_n whose Kazhdan-Lusztig and Poincare polynomials and the singular loci of whose Schubert varieties have certain fairly simple and explicit descriptions. This paper provides a 7-term linear recurrence relation leading to an explicit enumeration of the 321-hex permutations. A complete description of the corresponding generating tree is obtained as a by-product of enumeration techniques used in the paper, including Schensted's 321-subsequences decomposition, a 5-parameter generating function and the symmetries of the octagonal patterns avoided by the 321-hex permutations. | |
| dc.description | 21 pages, 12 figures. submitted to Discrete Mathematics | |
| dc.identifier | https://arxiv.org/abs/math/0106073 | |
| dc.identifier | http://arxiv.org/abs/math/0106073 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/61623 | |
| dc.subject | Combinatorics | |
| dc.title | Explicit Enumeration of 321,Hexagon-Avoiding Permutations | |
| dc.type | text |