Lefschetz decomposition and the cd-index of fans
| dc.creator | Karu, Kalle | |
| dc.date | 2005-09-09 | |
| dc.date.accessioned | 2026-07-07T05:23:06Z | |
| dc.date.available | 2026-07-07T05:23:06Z | |
| dc.description | The goal of this article is to give a Lefschetz type decomposition for the cd-index of a complete fan. To a complete simplicial fan one can associate a toric variety X, the even Betti numbers h_i of X and the numbers g_i = h_i-h_{i-1}. If the fan is projective, then non-negativity of g_i follows from the Lefschetz decomposition of the cohomology. In the case of a nonsiplicial complete fan one can analogously compute the flag h-numbers h_S and, by a change of variable formula, the cd-index. We give an analogue of the Lefschetz operation for the cd-index. This gives another proof of the non-negativity of the cd-index for complete fans. | |
| dc.description | 14 pages, 1 figure | |
| dc.identifier | https://arxiv.org/abs/math/0509220 | |
| dc.identifier | http://arxiv.org/abs/math/0509220 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/76306 | |
| dc.subject | Algebraic Geometry | |
| dc.subject | Combinatorics | |
| dc.subject | 14M25; 06A07 | |
| dc.title | Lefschetz decomposition and the cd-index of fans | |
| dc.type | text |