The recent interest both in partitions of finite geometries into other geometric objects and in the classical Segre varieties over finite fields are the background motivation for this paper. More precisely, partitions of Segre varieties into Segre varieties are investigated and the idea of nested partitions is introduced. Other partitions, namely of projective spaces and hyperbolic quadrics, ar...

We prove the existence of defective secant varieties of three-factor and four-factor Segre-Veronese varieties embedded in certain multi-degree. These defective secant varieties were previously unknown and are of importance in the classification of defective secant varieties of Segre-Veronese varieties with three or more factors.

Considerations based on the known relation between different characteristic classes for singular hypersufaces suggest that a form of the ‘inclusionexclusion’ principle may hold for Segre classes. We formulate and prove such a principle for a notion closely related to Segre classes. This is used to provide a simple computation of the classes introduced in [Alu], in certain special (but represent...

In this paper, we explore holomorphic Segre preserving maps. First, we investigate holomorphic Segre preserving maps sending the complexificationM of a generic real analytic submanifold M ⊆ C of finite type at some point p into the complexification M′ of a generic real analytic submanifold M ′ ⊆ C ′ , finitely nondegenerate at some point p. We prove that for a fixed M and M , the germs at (p, p̄...

We define a power series associated with a homogeneous ideal in a polynomial ring, encoding information on the Segre classes defined by extensions of the ideal in projective spaces of arbitrarily high dimension. We prove that this power series is rational, with poles corresponding to generators of the ideal, and with numerator of bounded degree and with nonnegative coefficients. We also prove t...

This paper studies the dimension of secant varieties to Segre varieties. The problem is cast both in the setting of tensor algebra and in the setting of algebraic geometry. An inductive procedure is built around the ideas of successive specializations of points and projections. This reduces the calculation of the dimension of the secant variety in a high dimensional case to a sequence of calcul...

We study a class obtained from the Segre class s(Z, Y ) of an embedding of schemes by incorporating the datum of a line bundle on Z. This class satisfies basic properties analogous to the ordinary Segre class, but leads to remarkably simple formulas in standard intersection-theoretic situations such as excess or residual intersections. We prove a formula for the behavior of this class under lin...

Considerations based on the known relation between di erent characteristic classes for singular hypersufaces suggest that a form of the `inclusionexclusion' principle may hold for Segre classes. We formulate and prove such a principle for a notion closely related to Segre classes. This is used to provide a simple computation of the classes introduced in [Alu], in certain special (but representa...