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Sabir M. Gusein-Zade

Publications and source records attributed to Sabir M. Gusein-Zade.

At least 37 records · Page 2Linked to original sources
arXiv2015

Enhanced equivariant Saito duality

In a previous paper, the authors defined an equivariant version of the so-called Saito duality between the monodromy zeta functions as a sort of Fourier transform between the Burnside rings of an abelian group and of its group of characters. Here a so-called enhanced Burnside ring $\widehat{B}(G)$ of a finite group $G$ is defined. An element of it is represented by a finite $G$-set with a $G$-equivariant transformation and with characters of the isotropy subgroups associated to all points. One gives an enhanced version of the equivariant Saito duality. For a complex analytic $G$-manifold with a $G$-equivariant transformation of it one has an enhanced equivariant Euler characteristic with values in a completion of $\widehat{B}(G)$. It is proved that the (reduced) enhanced equivariant Euler characteristics of the Milnor fibres of Berglund-Hübsch dual invertible polynomials coincide up to sign and show that this implies the result about orbifold zeta functions of Berglund-Hübsch-Henningson dual pairs obtained earlier.

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arXiv2014

An equivariant version of the Euler obstruction

For a complex analytic variety with an action of a finite group and for an invariant 1-form on it, we give an equivariant version (with values in the Burnside ring of the group) of the local Euler obstruction of the 1-form and describe its relation with the equivariant radial index defined earlier. This leads to equivariant versions of the local Euler obstruction of a complex analytic space and of the global Euler obstruction.

math.AG↗
arXiv2014

Indices of collections of equivariant 1-forms and characteristic numbers

If two G-manifolds are G-cobordant then characteristic numbers corresponding to the fixed point sets (submanifolds) of subgroups of G and to normal bundles to these sets coincide. We construct two analogues of these characteristic numbers for singular complex G-varieties where G is a finite group. They are defined as sums of certain indices of collections of 1-forms (with values in the spaces of the irreducible representations of subgroups). These indices are generalizations of the GSV-index (for isolated complete intersection singularities) and the Euler obstruction respectively.

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arXiv2013

Equivariant indices of vector fields and 1-forms

Equivariant versions of the radial index and of the GSV-index of a vector field or a 1-form on a singular variety with an action of a finite group are defined. They have values in the Burnside ring of the group. Poincaré-Hopf type theorems for them are proven and some of their properties are described.

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arXiv2012

On an equivariant analogue of the monodromy zeta function

We offer an equivariant analogue of the monodromy zeta function of a germ invariant with respect to an action of finite group G as an element of the Grothendieck ring of finite (Z x G)-sets. We formulate equivariant analogues of the Sebastiani-Thom theorem and of the A'Campo formula.

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arXiv2012

On a Newton filtration for functions on a curve singularity

In a previous paper, there was defined a multi-index filtration on the ring of functions on a hypersurface singularity corresponding to its Newton diagram generalizing (for a curve singularity) the divisorial one. Its Poincaré series was computed for plane curve singularities non-degenerate with respect to their Newton diagrams. Here we use another technique to compute the Poincaré series for plane curve singularities without the assumption that they are non-degenerate with respect to their Newton diagrams. We show that the Poincaré series only depends on the Newton diagram and not on the defining equation.

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arXiv2011

Orbifold Euler characteristics for dual invertible polynomials

To construct mirror symmetric Landau-Ginzburg models, P.Berglund, T.Hübsch and M.Henningson considered a pair $(f,G)$ consisting of an invertible polynomial $f$ and an abelian group $G$ of its symmetries together with a dual pair $(\widetilde{f}, \widetilde{G})$. Here we study the reduced orbifold Euler characteristics of the Milnor fibres of $f$ and $\widetilde f$ with the actions of the groups $G$ and $\widetilde G$ respectively and show that they coincide up to a sign.

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arXiv2011

Saito duality between Burnside rings for invertible polynomials

We give an equivariant version of the Saito duality which can be regarded as a Fourier transformation on Burnside rings. We show that (appropriately defined) reduced equivariant monodromy zeta functions of Berglund-Hübsch dual invertible polynomials are Saito dual to each other with respect to their groups of diagonal symmetries. Moreover we show that the relation between "geometric roots" of the monodromy zeta functions for some pairs of Berglund-Hübsch dual invertible polynomials described in a previous paper is a particular case of this duality.

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arXiv2010

Monodromy of dual invertible polynomials

A generalization of Arnold's strange duality to invertible polynomials in three variables by the first author and A.Takahashi includes the following relation. For some invertible polynomials $f$ the Saito dual of the reduced monodromy zeta function of $f$ coincides with a formal "root" of the reduced monodromy zeta function of its Berglund-Hübsch transpose $f^T$. Here we give a geometric interpretation of "roots" of the monodromy zeta function and generalize the above relation to all non-degenerate invertible polynomials in three variables and to some polynomials in an arbitrary number of variables in a form including "roots" of the monodromy zeta functions both of $f$ and $f^T$.

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arXiv2010

On divisorial filtrations associated with Newton diagrams

We consider divisorial filtration on the rings of functions on hypersurface singularities associated with Newton diagrams and their analogues for plane curve singularities. We compute the multi-variable Poincaré series for the latter ones.

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arXiv2010

Klein Foams

Klein foams are analogues of Riemann and Klein surfaces with one-dimensional singularities. We prove that the field of dianalytic functions on a Klein foam $Ω$ coincides with the field of dianalytic functions on a Klein surface $K_Ω$. We construct the moduli space of Klein foams and we prove that the set of classes of topologically equivalent Klein foams form an analytic space homeomorphic to $\mathbb{R}^{n}/\mathsf{Mod}$, where $\mathsf{Mod}$ is a discrete group.

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arXiv2006

Indices of vector fields and 1-forms on singular varieties

We discuss different generalizations of the classical notion of the index of a singular point of a vector field to the case of vector fields or 1-forms on singular varieties, describe relations between them and formulae for their computation.

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arXiv2005

Quadratic forms for a 1-form on an isolated complete intersection singularity

We consider a holomorphic 1-form $ω$ with an isolated zero on an isolated complete intersection singularity $(V,0)$. We construct quadratic forms on an algebra of functions and on a module of differential forms associated to the pair $(V,ω)$. They generalize the Eisenbud-Levine-Khimshiashvili quadratic form defined for a smooth $V$.

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arXiv2004

Integration over spaces of non-parametrized arcs and motivic versions of the monodromy zeta function

We elaborate notions of integration over the space of arcs factorized by the natural $C^*$-action and over the space of non-parametrized arcs (branches). There are offered two motivic versions of the zeta function of the classical monodromy transformation of a germ of an analytic function on a smooth space. We indicate a direct formula which connects the naive motivic zeta function of J. Denef and F. Loeser with the classical monodromy zeta function.

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arXiv2004

Power structure over the Grothendieck ring of varieties and generating series of Hilbert schemes of points

The power structure over the Grothendieck (semi)ring of complex quasi-projective varieties constructed by the authors is used to express the generating series of classes of Hilbert schemes of zero-dimensional subschemes on a smooth quasi-projective variety as an exponent of that for the complex affine space of the same dimension. Specializations of this relation give formulae for generating series of such invariants of the Hilbert schemes of points as the Euler characteristic and the Hodge-Deligne polynomial.

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