37 research outputs found
On the degree of Polar Transformations -- An approach through Logarithmic Foliations
We investigate the degree of the polar transformations associated to a
certain class of multi-valued homogeneous functions. In particular we prove
that the degree of the pre-image of generic linear spaces by a polar
transformation associated to a homogeneous polynomial is determined by the
zero locus of . For zero dimensional-dimensional linear spaces this was
conjecture by Dolgachev and proved by Dimca-Papadima using topological
arguments. Our methods are algebro-geometric and rely on the study of the Gauss
map of naturally associated logarithmic foliations
On the height of foliated surfaces with vanishing Kodaira dimension
We prove that the height of a foliated surface of Kodaira dimension zero belongs to {1, 2, 3, 4, 5, 6, 8, 10, 12}. We also construct an explicit projective model for Brunella's very special foliation
Closed meromorphic 1-forms
We review properties of closed meromorphic -forms and of the foliations
defined by them. We present and explain classical results from foliation
theory, like index theorems, the existence of separatrices, and resolution of
singularities under the lenses of the theory of closed meromorphic -forms
and flat meromorphic connections. We apply the theory to investigate the
algebraicity separatrices in a semi-global setting (neighborhood of a compact
curve contained in the singular set of the foliation), and the geometry of
smooth hypersurfaces with numerically trivial normal bundle on compact K\"ahler
manifolds
Vector Fields, Invariant Varieties and Linear Systems
We investigate the interplay between invariant varieties of vector fields and
the inflection locus of linear systems with respect to the vector field. Among
the consequences of such investigation we obtain a computational criteria for
the existence of rational first integrals of a given degree, bounds for the
number of first integrals on families of vector fields and a generalization of
Darboux's criteria. We also provide a new proof of Gomez-Mont's result on
foliations with all leaves algebraic.Comment: 15 pages, Late
Codimension one foliations in positive characteristic
We investigate the geometry of codimension one foliations on smooth
projective varieties defined over fields of positive characteristic with an eye
toward applications to the structure of codimension one holomorphic foliations
on projective manifolds