Generalized Noncrossing Partitions and Combinatorics of Coxeter Groups
| dc.creator | Armstrong, Drew | |
| dc.date | 2006-11-04 | |
| dc.date | 2007-10-18 | |
| dc.date.accessioned | 2026-07-07T08:36:57Z | |
| dc.date.available | 2026-07-07T08:36:57Z | |
| dc.description | This memoir constitutes the author's PhD thesis at Cornell University. It serves both as an expository work and as a description of new research. At the heart of the memoir, we introduce and study a poset $NC^{(k)}(W)$ for each finite Coxeter group $W$ and for each positive integer $k$. When $k=1$, our definition coincides with the generalized noncrossing partitions introduced by Brady-Watt and Bessis. When $W$ is the symmetric group, we obtain the poset of classical $k$-divisible noncrossing partitions, first studied by Edelman. Along the way, we include a comprehensive introduction to related background material. Before defining our generalization $NC^{(k)}(W)$, we develop from scratch the theory of algebraic noncrossing partitions $NC(W)$. This involves studying a finite Coxeter group $W$ with respect to its generating set $T$ of {\em all} reflections, instead of the usual Coxeter generating set $S$. This is the first time that this material has appeared in one place. Finally, it turns out that our poset $NC^{(k)}(W)$ shares many enumerative features in common with the ``generalized nonnesting partitions'' of Athanasiadis and the ``generalized cluster complexes'' of Fomin and Reading. In particular, there is a generalized ``Fuss-Catalan number'', with a nice closed formula in terms of the invariant degrees of $W$, that plays an important role in each case. We give a basic introduction to these topics, and we describe several conjectures relating these three families of ``Fuss-Catalan objects''. | |
| dc.description | Final version -- to appear in Memoirs of the American Mathematical Society. Many small improvements in exposition, especially in Sections 2.2, 4.1 and 5.2.1. Section 5.1.5 deleted. New references to recent work | |
| dc.identifier | https://arxiv.org/abs/math/0611106 | |
| dc.identifier | http://arxiv.org/abs/math/0611106 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/140244 | |
| dc.subject | Combinatorics | |
| dc.subject | Group Theory | |
| dc.subject | 05E15; 05E25; 05A18; 05-02 | |
| dc.title | Generalized Noncrossing Partitions and Combinatorics of Coxeter Groups | |
| dc.type | text |