منابع مشابه
Birational morphisms and Poisson moduli spaces
We study birational morphisms between smooth projective surfaces that respect a given Poisson structure, with particular attention to induced birational maps between the (Poisson) moduli spaces of sheaves on those surfaces. In particular, to any birational morphism, we associate a corresponding “minimal lift” operation on sheaves of homological dimension ≤ 1, and study its properties. In partic...
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Smooth toric Fano varieties are classified up to dimension 4. In dimension 2, there are five toric Del Pezzo surfaces: P, P1×P1, and Si, the blowup of P in i points, for i = 1, 2, 3. There are 18 toric Fano 3-folds [2, 20] and 124 toric Fano 4-folds [4, 17]. In higher dimensions, little is known about them and many properties that hold in low dimensions are not known to hold in general. Let X b...
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In this article, we study birational varieties with 1-dimensional foliation and induced piecewise morphisms. Let X and Y be smooth complete complex varieties. Consider a birational map f : X · · · → Y . By definition, f is not generally defined all over X. We observe that if X has some one-dimensional foliation, it is possible to extend f to the whole space X as a piecewise morphism (that is, a...
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It is known that any factorization of a local birational morphism f: Spec 5 —» SpecJ? of nonsingular (affine) schemes of arbitrary dimension via other nonsingular schemes must be finite in length. This fact generalizes the classical Local Factorization Theorem of Zariski and Abhyankar, which states that there is a unique such factorization, that given by quadratic transformations, in the surfac...
متن کاملSignature Schemes Based on Birational Permutations
Many public key cryptographic schemes (such a s c u b i c RSA) are based on low degree polynomials whose inverses are high degree polynomials. These functions are very easy to compute but time consuming to invert even by their legitimate users. To m a k e such s c hemes more eecient, we consider in this paper the class of birational permutations f over k-tuples of numbers, in which both f and f...
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ژورنال
عنوان ژورنال: Forum of Mathematics, Sigma
سال: 2019
ISSN: 2050-5094
DOI: 10.1017/fms.2019.6