Complex Intersections of Real Cycles in Real Algebraic Varieties and Generalized ArnoldViro Inequalities
Abstract
Consider a real algebraic variety, $\R X$, of dimension $d$. If its complexification, $\C X$, is a rational homology manifold (at least in a neighborhood of $\R X$), then the intersection form in $\C X$ defines a bilinear form in $d$homologies of $\R X$. Analizing it, one can obtain an information about $\R X$, as it was done by V.I.Arnold in the case of nonsingular double planes and then generalized by O.Ya.Viro and V.M.Kharlamov to the nodal surfaces. I present an integration (based on the Euler characteristic) formula, which expresses this form in terms of a certain local inveriant of the real singularities (which is, essentially, the local version of this form). I give a few methods to calculate this invariant in the case of surface singularities and analyze its properties in the higher dimensional case. The results are applied, for instance, to the double coverings over a projective space, branched along simple arrangements of hyperplanes.
 Publication:

arXiv Mathematics eprints
 Pub Date:
 February 1999
 arXiv:
 arXiv:math/9902022
 Bibcode:
 1999math......2022F
 Keywords:

 Mathematics  Algebraic Geometry;
 Mathematics  Geometric Topology
 EPrint:
 44 pages, AMSTeX, no figures