Displaying similar documents to “Basepoint freeness for nef and big line bundles in positive characteristic.”

Threefolds with nef anticanonical bundles.

Thomas Peternell, Fernando Serrano (1998)

Collectanea Mathematica

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In this paper we study the global structure of projective threefolds X whose anticanonical bundle -KX is nef.

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...

Effective nonvanishing, effective global generation

Mark Andrea A. De Cataldo (1998)

Annales de l'institut Fourier

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We prove a multiple-points higher-jets nonvanishing theorem by the use of local Seshadri constants. Applications are given to effectivity problems such as constructing rational and birational maps into Grassmannians, and the global generation of vector bundles.