منابع مشابه
Singularities Appearing on Generic Fibers of Morphisms between Smooth Schemes
I give various criteria for singularities to appear on geometric generic fibers of morphism between smooth schemes in positive characteristics. This involves local fundamental groups, jacobian ideals, projective dimension, tangent and cotangent sheaves, and the effect of Frobenius. As an application, I determine which rational double points do appear on geometric generic fibers.
متن کاملExtensions of Raynaud Schemes with Trivial Generic Fibers
We calculate the number of extensions of Raynaud schemes over the ring of integers of an absolutely ramified p-adic field with the trivial generic fibers by counting the rational points of the moduli space of finite flat models. Introduction Let K be a totally ramified extension of degree e over Qp for p > 2, and F be a finite field of characteristic p. We consider the constant group scheme CF ...
متن کاملIntegral Points on Generic Fibers
Let P (x, y) be a rational polynomial. If the curve (P (x, y) = k), k ∈ Q, is irreducible and admits an infinite number of points whose coordinates are integers, Siegel’s theorem implies that the curve is rational. We deal with the case where k is a generic value and prove, in the spirit of the Abhyankar-MohSuzuki theorem, that there exists an algebraic automorphism sending P (x, y) to the poly...
متن کاملGeneric fibrations around multiple fibers
Given some type of fibration on a 4-manifold X with a torus regular fiber T , we may produce a new 4-manifold XT by performing torus surgery on T . There is a natural way to extend the fibration to XT , but a multiple fiber (nongeneric) singularity is introduced. We construct explicit generic fibrations (with only indefinite fold singularities) in a neighborhood of this multiple fiber. As an ap...
متن کاملGeneric Attacks on Feistel Schemes
Let A be a Feistel scheme with 5 rounds from 2n bits to 2n bits. In the present paper we show that for most such schemes A: 1. It is possible to distinguish A from a random permutation from 2n bits to 2n bits after doing at most O(2n) computations with O(2n) non-adaptive chosen plaintexts. 2. It is possible to distinguish A from a random permutation from 2n bits to 2n bits after doing at most O...
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: Journal of Algebra
سال: 1999
ISSN: 0021-8693
DOI: 10.1006/jabr.1998.7656