Hyperplanes and hyperplane complements in the Segre product of partial linear spaces are investigated. The parallelism of such a complement is characterized in terms of the point-line incidence. Assumptions, under which the automorphisms of the complement are the restrictions of the automorphisms of the ambient space, are given. An affine covering for the Segre product of Veblenian gamma spaces...

Holey Segre varieties are introduced, which generalize classical Segre varieties and whose existence is suggested by the fact that any non-prime finite field contains proper subfields. More precisely, a holey Segre variety is the tensor product PG(n, q) ⊗ PG(m, qk ). An algebraic description of such an object is given and its structure is investigated. Furthermore, special choices of the parame...

Let K = Fq be a finite field. We introduce a family of projective Reed-Mullertype codes called projective Segre codes. Then we study their basic parameters and show that they are direct products of projective Reed-Muller-type codes. It turns out that the direct product of two projective Reed-Muller-type codes is again a projective Reed-Muller-type code. As a consequence we recover some results ...

The aim of this paper is to investigate properties of the local cohomology of rings of mixed characteristic that are analogous to Segre products of rings de ned over a eld. The main question is whether the local cohomology can be almost killed in a nite extension (we de ne what this means below). There are two reasons for considering this type of ring. First, there are special properties of the...

We study the syzygies of the ideals of the Segre embeddings. Let d ∈ N, d ≥ 3; we prove that the line bundle O(1, ..., 1) on the P 1 × ....× P 1 (d copies) satisfies Property Np of GreenLazarsfeld if and only if p ≤ 3. Besides we prove that if we have a projective variety not satisfying Property Np for some p, then the product of it with any other projective variety does not satisfy Property Np...

In this paper we characterize the automorphisms (collineations) of the Segre product of partial linear spaces. In particular, we show that if all components of the product are strongly connected, then every collineation is determined by a set of isomorphisms between its components. The formalization follows the ideas presented in the Journal of Geometry paper [16] by Naumowicz and Prażmowski.

§1. Geometry of finite type and review of CR-extension theory . . . . .2. §2. Identification of CR vector fields and of Segre varieties . . . . . . . . . .4. §3. Segre varieties and extrinsic complexification . . . . . . . . . . . . . . . . . . . .10. §4. Segre sets and iterated complexifications . . . . . . . . . . . . . . . . . . . . . . . . .12. §5. Segre varieties and conjugate Segre variet...

In this paper we give a nice formula for the CastelnuovoMumford regularity of the Segre product of modules, under some suitable hypotheses. This extends recent results of David A. Cox, and Evgeny Materov (2009).