{ "id": "1507.02090", "version": "v1", "published": "2015-07-08T10:25:36.000Z", "updated": "2015-07-08T10:25:36.000Z", "title": "Exponential formulas for models of complex reflection groups", "authors": [ "Giovanni Gaiffi" ], "categories": [ "math.CO", "math.AT" ], "abstract": "In this paper we find some exponential formulas for the Betti numbers of the De Concini-Procesi minimal wonderful models Y_{G(r,p,n)} associated to the complex reflection groups G(r,p,n). Our formulas are different from the ones already known in the literature: they are obtained by a new combinatorial encoding of the elements of a basis of the cohomology by means of set partitions with weights and exponents. We also point out that a similar combinatorial encoding can be used to describe the faces of the real spherical wonderful models of type A_{n-1}=G(1,1,n), B_n=G(2,1,n) and D_n=G(2,2,n). This provides exponential formulas for the f-vectors of the associated nestohedra: the Stasheff's associahedra (in this case closed formulas are well known) and the graph associahedra of type D_n.", "revisions": [ { "version": "v1", "updated": "2015-07-08T10:25:36.000Z" } ], "analyses": { "keywords": [ "complex reflection groups", "exponential formulas", "concini-procesi minimal wonderful models", "betti numbers", "stasheffs associahedra" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }