Let X be a variety with terminal singularities of dimension n. We study local contractions f: X → Z supported by a ℚ-Cartier divisor of the type KX + τL, where L is an f-ample Cartier divisor and τ > 0 is a rational number. Equivalently, f is a Fano-Mori contraction associated to an extremal face in NE(X)KX+τL=0. We prove that, if τ > (n - 3) > 0, the general element X′ ϵ \L\ is a variety with at most terminal singularities. We apply this to characterize, via an inductive argument, some birational contractions as above with τ > (n - 3) > 0.

Local Fano-Mori contractions of high nef-value / M. Andreatta, L. Tasin. - In: MATHEMATICAL RESEARCH LETTERS. - ISSN 1073-2780. - 23:5(2016), pp. 1247-1262. [10.4310/MRL.2016.v23.n5.a1]

Local Fano-Mori contractions of high nef-value

L. Tasin
2016

Abstract

Let X be a variety with terminal singularities of dimension n. We study local contractions f: X → Z supported by a ℚ-Cartier divisor of the type KX + τL, where L is an f-ample Cartier divisor and τ > 0 is a rational number. Equivalently, f is a Fano-Mori contraction associated to an extremal face in NE(X)KX+τL=0. We prove that, if τ > (n - 3) > 0, the general element X′ ϵ \L\ is a variety with at most terminal singularities. We apply this to characterize, via an inductive argument, some birational contractions as above with τ > (n - 3) > 0.
Mathematics (all)
Settore MAT/03 - Geometria
2016
Article (author)
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/638202
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