4,699 research outputs found
Hypergeometric periods for a tame polynomial
We analyse the Gauss-Manin system of differential equations---and its Fourier
transform---attached to regular functions satisfying a tameness assupmption on
a smooth affine variety over C (e.g. tame polynomials on C^{n+1}). We give a
solution to the Birkhoff problem and prove Hodge-type results analogous to
those existing for germs of isolated hypersurface singularities.Comment: AMS-LaTeX with amsart.sty. Uses XY-pic package. 43 page
Fourier-Laplace transform of irreducible regular differential systems on the Riemann sphere
We show that the Fourier-Laplace transform of an irreducible regular
differential system on the Riemann sphere underlies, when one only considers
the part at finite distance, a polarizable regular twistor
-module. The associated holomorphic bundle out of the origin is
therefore equipped with a natural harmonic metric with a tame behaviour near
the origin.Comment: 13+11 pages, AMSlatex. Original version followed by an Erratum added
may 2007 after publicatio
Wild twistor D-modules
We propose a definition of (polarized) wild twistor D-modules, generalizing
to objects with irregular singularities that of (polarized) regular twistor
D-modules. We give a precise analysis in dimension one.Comment: 49 pages, revised versio
Differential systems of pure Gaussian type
We give the transformation rule for the Stokes data of the Laplace transform
of a differential system of pure Gaussian type.Comment: 31 pages. V2: final version to appear in Izv. Mat
On a twisted de Rham complex
We show that, given a projective regular function f on a smooth
quasi-projective variety over C, the corresponding cohomology groups of the
algebraic de Rham complex with twisted differential d-df and of the complex of
algebraic forms with differential df have the same dimension (a result
announced by Barannikov and Kontsevitch). We generalize the result to de Rham
complexes with coefficients in a mixed Hodge Module.Comment: AMS-LaTeX with amsart.sty. 15 page
Kontsevich's conjecture on an algebraic formula for vanishing cycles of local systems
For a local system and a function on a smooth complex algebraic variety, we
give a proof of a conjecture of M. Kontsevich on a formula for the vanishing
cycles using the twisted de Rham complex of the formal microlocalization of the
corresponding locally free sheaf with integrable connection having regular
singularity at infinity. We also prove its local version, which may be viewed
as a natural generalization of a result of E. Brieskorn in the isolated
singularity case. We then generalize these to the case of the de Rham complexes
of regular holonomic D-modules where we have to use the tensor product with a
certain sheaf of formal microlocal differential operators instead of the formal
completion.Comment: 23 pages, this improves and generalizes some results in
arXiv:1012.3818; v2, abstract is modified, and Cor. 1 and 3.4-5 are added;
v3, Remark 3.6 adde
Gauss-Manin systems, Brieskorn lattices and Frobenius structures (II)
We give an explicit description of the canonical Frobenius structure attached
(by the results of the first part of this article) to the polynomial
f(u_0,...,u_n)=w_0u_0+...+w_nu_n restricted to the torus
u_0^{w_0}...u_n^{w_n}=1, for any family of positive integers w_0,...,w_n such
that gcd(w_0,...,w_n)=1.Comment: 22 pages, 3 figures, LaTeX + smf classes available at
http://smf.emath.fr/Publications/Formats/index.html Typos correcte
Semicontinuity of the spectrum at infinity
We prove that, for an analytic family of ``weakly tame'' regular functions on
an affine manifold, the spectrum at infinity of each function of the family is
semicontinuous in the sense of Varchenko.Comment: AMS-LaTeX with amsart.sty. 10 page
The local Laplace transform of an elementary irregular meromorphic connection
We give a definition of the topological local Laplace transformation for a
Stokes-filtered local system on the complex affine line and we compute in a
topological way the Stokes data of the Laplace transform of a differential
system of elementary type.Comment: 56 pages, 21 figures. V2: Final version to appear in Rend. Sem. Mat.
Univ. Padov
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