In this paper we find exponential formulas for the Betti numbers of the De Concini-Procesi minimal wonderful models YG(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 An-1(=G(1, 1, n)), Bn (=G(2, 1, n)) and Dn(=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 Dn.
Exponential formulas for models of complex reflection groups
GAIFFI, GIOVANNI
2016-01-01
Abstract
In this paper we find exponential formulas for the Betti numbers of the De Concini-Procesi minimal wonderful models YG(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 An-1(=G(1, 1, n)), Bn (=G(2, 1, n)) and Dn(=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 Dn.File | Dimensione | Formato | |
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