Displaying similar documents to “Bounds on Castelnuovo-Mumford regularity for divisors on rational normal scrolls.”

Special effect varieties in higher dimension.

Cristiano Bocci (2005)

Collectanea Mathematica

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Here we introduce the concept of special effect varieties in higher dimension and we generalize to P, n ≥ 3, the two conjectures given in [2] for the planar case. Finally, we propose some examples on the product of projective spaces and we show how these results fit with the ones of Catalisano, Geramita and Gimigliano.

Segre-Veronese embeddings of P x P x P and their secant varieties.

Maria Virginia Catalisano, Anthony V. Geramita, Alessandro Gimigliano (2007)

Collectanea Mathematica

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In this paper we compute the dimension of all the s higher secant varieties of the Segre-Veronese embeddings Y of the product P × P × P in the projective space P via divisors of multidegree d = (a,b,c) (N = (a+1)(b+1)(c+1) - 1). We find that Y has no deficient higher secant varieties, unless d = (2,2,2) and s = 7, or d = (2h,1,1) and s = 2h + 1, with defect 1 in both cases.