共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
In this paper we develop a very explicit theory of ramification of general valuations in algebraic function fields. In characteristic zero and arbitrary dimension, we obtain the strongest possible generalization of the classical ramification theory of local Dedekind domains. We further develop a ramification theory of algebraic functions fields of dimension two in positive characteristic. We prove that local monomialization and simultaneous resolution hold under very mild assumptions, and give pathological examples. 相似文献
3.
We apply tools coming from singularity theory, as Hamburger–Noether expansions, and from valuation theory, as generating sequences, to explicitly describe order functions given by valuations of 2-dimensional function fields. We show that these order functions are simple when their ordered domains are isomorphic to the value semigroup algebra of the corresponding valuation. Otherwise, we provide parametric equations to compute them. In the first case, we construct, for each order function, families of error correcting codes which can be decodified by the Berlekamp–Massey–Sakata algorithm and we give bounds for their minimum distance depending on minimal sets of generators for the above value semigroup. 相似文献
4.
Dušan Repovš Pavel V. Semenov 《Journal of Mathematical Analysis and Applications》2007,334(1):646-655
Let and be any convex-valued lower semicontinuous mappings and let be any linear surjection. The splitting problem is the problem of representation of any continuous selection f of the composite mapping L(F1;F2) in the form f=L(f1;f2), where f1 and f2 are some continuous selections of F1 and F2, respectively. We prove that the splitting problem always admits an approximate solution with fi being an ε-selection (Theorem 2.1). We also propose a special case of finding exact splittings, whose occurrence is stable with respect to continuous variations of the data (Theorem 3.1) and we show that, in general, exact splittings do not exist even for the finite-dimensional range. 相似文献
5.
Ignacio Cascos 《Computational Statistics》2007,22(4):557-569
Given a data set in the multivariate Euclidean space, we study regions of central points built by averaging all their subsets
with a fixed number of elements. The averaging of these sets is performed by appropriately scaling the Minkowski or elementwise
summation of their convex hulls. The volume of such central regions is proposed as a multivariate scatter estimate and a circular
sequence algorithm to compute the central regions of a bivariate data set is described.
Extended version of the conference paper Cascos (2006) presented at the 17th Conference of the European Regional Section of
the International Association for Statistical Computing (COMPSTAT 2006, Rome, Italy, August 28–September 1, 2006).
Supported by the Spanish Ministry of Education and Science under grant MTM2005-02254. 相似文献
6.
Let w be an element of the Weyl group of sl
n + 1. We prove that for a certain class of elements w (which includes the longest element w0 of the Weyl group), there exist a lattice polytope R
l(w)
, for each fundamental weight i of sl
n + 1, such that for any dominant weight =
i = 1
n
a
i
i
, the number of lattice points in the Minkowski sum
w
=
i = 1
n
a
i
i
w
is equal to the dimension of the Demazure module E
w
(). We also define a linear map A
w
: R
l(w)
P Z R where P denotes the weight lattice, such that char E
w
() = e
e–A(x)
where the sum runs through the lattice points x of
w
. 相似文献
7.
Ning Xu 《数学学报(英文版)》2011,27(7):1305-1314
In this paper, we show that all the nontrivial valuations on surfaces can be given by the infinite sequences of blowing-ups,
and give the process of blowing-ups. 相似文献
8.
9.
Daniel M. Oberlin 《Journal of Fourier Analysis and Applications》2008,14(3):484-491
For k≥d/2 we give examples of measures on k-surfaces in ℝ
d
. These measures satisfy convolution estimates which are nearly optimal.
The author was supported in part by NSF grant DMS-0552041. 相似文献
10.
In this work we present some new results on convolution and subordination in geometric function theory. We prove that the class of convex functions of order α is closed under convolution with a prestarlike function of the same order. Using this, we prove that subordination under the convex function order α is preserved under convolution with a prestarlike function of the same order. Moreover, we find a subordinating factor sequence for the class of convex functions. The work deals with several ideas and techniques used in geometric function theory, contained in the book Convolutions in Geometric Function Theory by Ruscheweyh (1982). 相似文献
11.
Gregory Budzban 《Journal of Mathematical Analysis and Applications》2006,317(2):698-706
Convolution products of probability measures are considered in the context of completely simple semigroups. Given a sequence of measures (μn)⊂Prob(S), where S is a finite completely simple semigroup, results are proven which (1) relate the supports of the measures in the sequence to the supports of the tail limit measures, and (2) determine necessary and sufficient conditions for convergence of the convolution products in the case of rectangular groups. An example showing how the theory can be used to analyze the convergence behavior of non-homogeneous Markov chains is included. 相似文献
12.
13.
14.
15.
Daniel M. Oberlin 《Journal of Functional Analysis》2010,259(7):1799-1815
We prove Lp→Lq convolution estimates for the affine arclength measure on certain flat curves in Rd when d∈{2,3,4}. For d=2,3, we also establish certain related Lorentz space estimates. 相似文献
16.
17.
J. Müller 《Constructive Approximation》1999,15(4):523-536
Taylor sections S
n
(f) of an entire function f often provide easy computable polynomial approximants of f . However, while the rate of convergence of (S
n
(f))
n
is nearly optimal on circles around the origin, this is no longer true for other plane sets as, for example, real compact
intervals. The aim of this paper is to construct for certain families of (entire) functions sequences of polynomial approximants
which are computable with essentially the same effort as Taylor sections and which have a better rate of convergence on some
parts of the plane. The resulting method may be applied, for example, to (modified) Bessel functions, to confluent hypergeometric
functions, or to parabolic cylinder functions.
October 2, 1997. Date revised: March 12, 1998. Date accepted: April 28, 1998. 相似文献
18.
P. Jiménez-Rodríguez S. Maghsoudi G.A. Muñoz-Fernández 《Journal of Mathematical Analysis and Applications》2014
In 1951 V. Jarník constructed two continuous functions whose Volterra convolution is nowhere differentiable. We generalize Jarník?s results by proving that the set of such functions is maximal lineable. This would shed some light on a question posed in 1973 on the structure of the set of continuous functions whose Volterra convolution is nowhere differentiable. 相似文献
19.
Susana Coré 《Journal of Mathematical Analysis and Applications》2010,370(2):472-485
Let G be a homogeneous group with homogeneous dimension Q, and let So denote the space of Schwartz functions on G with all moments vanishing. Let be the usual Euclidean Fourier transform. For j∈R, we let be the space of J, smooth away from 0, satisfying |α∂J(ξ)|?Cβ|ξ|j−|β|, where both |ξ| and |β| are taken in the homogeneous sense. We characterize , and show that as elements of . If j1,j2,j1+j2>−Q, one can replace So, by S, S′ in this result. A key ingredient of our proof is a lemma from the fundamental wavelet paper from 1985 by Frazier and Jawerth [4]. We believe that, in turn, our result will be useful in the theory of wavelets on homogeneous groups. 相似文献
20.
Stacey Muir 《Journal of Mathematical Analysis and Applications》2008,348(2):862-871
For two complex-valued harmonic functions f and F defined in the open unit disk Δ with f(0)=F(0)=0, we say f is weakly subordinate to F if f(Δ)⊂F(Δ). Furthermore, if we let E be a possibly infinite interval, a function with f(⋅,t) harmonic in Δ and f(0,t)=0 for each t∈E is said to be a weak subordination chain if f(Δ,t1)⊂f(Δ,t2) whenever t1,t2∈E and t1<t2. In this paper, we construct a weak subordination chain of convex univalent harmonic functions using a harmonic de la Vallée Poussin mean and a modified form of Pommerenke's criterion for a subordination chain of analytic functions. 相似文献