{ "id": "0709.4241", "version": "v3", "published": "2007-09-26T19:42:37.000Z", "updated": "2008-04-17T18:20:33.000Z", "title": "Permutahedra and generalized associahedra", "authors": [ "Christophe Hohlweg", "Carsten Lange", "Hugh Thomas" ], "comment": "27 pages, 10 figures; v3: 31 pages, 10 figures, Section 3 is rewritten, corrected typos, and updated references", "journal": "Advances in Math., 226 (2011), pp.608-640", "categories": [ "math.CO" ], "abstract": "Given a finite Coxeter system $(W,S)$ and a Coxeter element $c$, we construct a simple polytope whose outer normal fan is N. Reading's Cambrian fan $F_c$, settling a conjecture of Reading that this is possible. We call this polytope the $c$-generalized associahedron. Our approach generalizes Loday's realization of the associahedron (a type $A$ $c$-generalized associahedron whose outer normal fan is not the cluster fan but a coarsening of the Coxeter fan arising from the Tamari lattice) to any finite Coxeter group. A crucial role in the construction is played by the $c$-singleton cones, the cones in the $c$-Cambrian fan which consist of a single maximal cone from the Coxeter fan. Moreover, if $W$ is a Weyl group and the vertices of the permutahedron are chosen in a lattice associated to $W$, then we show that our realizations have integer coordinates in this lattice.", "revisions": [ { "version": "v3", "updated": "2008-04-17T18:20:33.000Z" } ], "analyses": { "subjects": [ "20F55", "06B99", "52B11", "05E99" ], "keywords": [ "generalized associahedron", "outer normal fan", "permutahedron", "approach generalizes lodays realization", "coxeter fan" ], "tags": [ "journal article" ], "publication": { "publisher": "Elsevier", "journal": "Adv. Math." }, "note": { "typesetting": "TeX", "pages": 27, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2007arXiv0709.4241H" } } }