منابع مشابه
AMPLE SUBVARIETIES AND q-AMPLE DIVISORS
We introduce a notion of ampleness for subschemes of any codimension using the theory of q-ample line bundles. We also investigate certain geometric properties satisfied by ample subvarieties, e.g. the Lefschetz hyperplane theorems and numerical positivity. Using these properties, we also construct a counterexample to the converse of the Andreotti-Grauert vanishing theorem.
متن کاملOn subvarieties with ample normal bundle
We show that a pseudoeffective R-divisor has numerical dimension 0 if it is numerically trivial on a subvariety with ample normal bundle. This implies that the cycle class of a curve with ample normal bundle is big, which gives an affirmative answer to a conjecture of Peternell. We also give other positivity properties of such subvarieties.
متن کاملAmple Sheaves and Ample Families
1 Ample Sheaves Let X be a scheme and L an invertible sheaf. Given a global section f ∈ Γ(X,L ) the set Xf = {x ∈ X | germxf / ∈ mxLx} is open (MOS,Lemma 29). The inclusion Xf −→ X is affine (RAS,Lemma 6) and in particular if X is an affine scheme then Xf is itself affine. Given a sequence of global sections f1, . . . , fn the open sets Xfi cover X if and only if the fi generate L (MOS,Lemma 32...
متن کاملThe Equations of Singular Loci of Ample Divisors on (subvarieties Of) Abelian Varieties
In this paper we consider ideal sheaves associated to the singular loci of a divisor in a linear system |L| of an ample line bundle on a complex abelian variety. We prove an effective result on their (continuous) global generation, after suitable twists by powers of L. Moreover we show that similar results hold for subvarieties of a complex abelian variety.
متن کاملAMPLE AND LEFT AMPLE SEMIGROUPS Extended
When E is actually the set of all idempotents of S, we drop the phrase “with respect to” and refer simply to the left or right ample condition. Recall that a partial permutation of a nonempty set X is a bijection σ : Y → Z for some subsets Y, Z of X, and that the set of all such partial permutations (denoted by IX) is a monoid under the usual composition of partial functions. Note that if σ : Y...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Advances in Mathematics
سال: 2012
ISSN: 0001-8708
DOI: 10.1016/j.aim.2012.02.001