Oleg Viro, Mutual Position of Hypersurfaces in Projective Space,  to appear in Arnold's Festschrift.

Abstract: In this paper elementary characteristics for mutual positions of several disjoint closed smooth two-dimensional manifold in the three-dimensional projective space are considered. In terms of these characteristics, new restrictions on topology of real algebraic surfaces of a given degree are formulated. Generalizations to the higher dimensions are indicated.