scholarly journals Asymptotic invariants of base loci

2006 ◽  
Vol 56 (6) ◽  
pp. 1701-1734 ◽  
Author(s):  
Lawrence Ein ◽  
Robert Lazarsfeld ◽  
Mircea Mustaţă ◽  
Michael Nakamaye ◽  
Mihnea Popa
Author(s):  
Ulrike Rieß

Abstract We approach non-divisorial base loci of big and nef line bundles on irreducible symplectic varieties. While for K3 surfaces, only divisorial base loci can occur, nothing was known about the behaviour of non-divisorial base loci for more general irreducible symplectic varieties. We determine the base loci of all big and nef line bundles on the Hilbert scheme of two points on very general K3 surfaces of genus two and on their birational models. Remarkably, we find an ample line bundle with a non-trivial base locus in codimension two. We deduce that, generically in the moduli spaces of polarized K3[2]-type varieties, the polarization is base point free.


2013 ◽  
Vol 10 (3) ◽  
pp. 2375-2422
Author(s):  
Miklós Abért ◽  
Damien Gaboriau ◽  
Andreas Thom

2020 ◽  
Vol 224 (12) ◽  
pp. 106447
Author(s):  
Antonio Laface ◽  
Luca Ugaglia
Keyword(s):  

2015 ◽  
Vol 159 (3) ◽  
pp. 517-527
Author(s):  
ANGELO FELICE LOPEZ

AbstractLet X be a normal projective variety defined over an algebraically closed field and let Z be a subvariety. Let D be an ${\mathbb R}$-Cartier ${\mathbb R}$-divisor on X. Given an expression (*) D$\sim_{\mathbb R}$t1H1 +. . .+ tsHs with ti ∈ ${\mathbb R}$ and Hi very ample, we define the (*)-restricted volume of D to Z and we show that it coincides with the usual restricted volume when Z$\not\subseteq$B+(D). Then, using some recent results of Birkar [Bir], we generalise to ${\mathbb R}$-divisors the two main results of [BCL]: The first, proved for smooth complex projective varieties by Ein, Lazarsfeld, Mustaţă, Nakamaye and Popa, is the characterisation of B+(D) as the union of subvarieties on which the (*)-restricted volume vanishes; the second is that X − B+(D) is the largest open subset on which the Kodaira map defined by large and divisible (*)-multiples of D is an isomorphism.


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