Corrado Zanella

Learn More
Let S(Π 0 , Π 1) be the product of the projective spaces Π 0 and Π 1 , i.e. the semilinear space whose point set is the product of the point sets of Π 0 and Π 1 , and whose lines are all products of the kind {P 0 } × g 1 or g 0 × {P 1 }, where P 0 , P 1 are points and g 0 , g 1 are lines. An embedding χ : S(Π 0 , Π 1) → Π is an injective mapping which maps(More)
In this paper both blocking sets with respect to the s-subspaces and covers with t-subspaces in a finite Grassmannian are investigated, especially focusing on geometric descriptions of blocking sets and covers of minimum size. When such a description exists, it is called a Bose–Burton type theorem. The canonical example of a blocking set with respect to the(More)
The aim of this paper is to present a construction of t-divisible designs for t > 3, because such divisible designs seem to be missing in the literature. To this end, tools such as finite projective spaces and their algebraic varieties are employed. More precisely, in a first step an abstract construction, called t-lifting, is developed. It starts from a(More)
The quadratic Veronese embedding ρ maps the point set P of PG(n, F) into the point set of PG(n+2 2 − 1, F) (F a commutative field) and has the following well-known property: If M ⊂ P, then the intersection of all quadrics containing M is the inverse image of the linear closure of M ρ. In other words, ρ transforms the closure from quadratic into linear. In(More)
Let χ be a linear morphism of the product of two projective spaces PG(n, F) and PG(m, F) into a projective space. Let γ be the Segre embedding of such a product. In this paper we give some sufficient conditions for the existence of an automorphism α of the product space and a linear morphism of projective spaces ϕ, such that γϕ = αχ. A.M.S. classification(More)