Displaying similar documents to “Geometric linear normality for nodal curves on some projective surfaces”

Grassmann defective surfaces

Claudio Fontanari (2004)

Bollettino dell'Unione Matematica Italiana

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A projective variety V is 1 , h -defective if the Grassmannian of lines contained in the span of h + 1 independent points on V has dimension less than the expected one. In the present paper, which is inspired by classical work of Alessandro Terracini, we prove a criterion of 1 , h -defectivity for algebraic surfaces and we discuss its applications to Veronese embeddings and to rational normal scrolls.

Some remarks on Set-theoretic Intersection Curves in P 3

Roberto Paoletti (1996)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Motivated by the notion of Seshadri-ampleness introduced in [11], we conjecture that the genus and the degree of a smooth set-theoretic intersection C ⊂ P 3 should satisfy a certain inequality. The conjecture is verified for various classes of set-theoretic complete intersections.

Seshadri positive curves in a smooth projective 3 -fold

Roberto Paoletti (1995)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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A notion of positivity, called Seshadri ampleness, is introduced for a smooth curve C in a polarized smooth projective 3 -fold X , A , whose motivation stems from some recent results concerning the gonality of space curves and the behaviour of stable bundles on P 3 under restriction to C . This condition is stronger than the normality of the normal bundle and more general than C being defined by a regular section of an ample rank- 2 vector bundle. We then explore some of the properties of Seshadri-ample...