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971.
J. Yoon 《Constructive Approximation》2001,17(2):227-247
A new multivariate approximation scheme on R
d
using scattered translates of the “shifted” surface spline function is developed. The scheme is shown to provide spectral
L
p
-approximation orders with 1 ≤ p ≤ ∞, i.e., approximation orders that depend on the smoothness of the approximands. In addition, it applies to noisy data
as well as noiseless data. A numerical example is presented with a comparison between the new scheme and the surface spline
interpolation method. 相似文献
972.
Roman Drnovšek 《Integral Equations and Operator Theory》2001,39(3):253-266
Let
be a collection of bounded operators on a Banach spaceX of dimension at least two. We say that
is finitely quasinilpotent at a vectorx
0X whenever for any finite subset
of
the joint spectral radius of
atx
0 is equal 0. If such collection
contains a non-zero compact operator, then
and its commutant
have a common non-trivial invariant, subspace. If in addition,
is a collection of positive operators on a Banach lattice, then
has a common non-trivial closed ideal. This result and a recent remarkable theorem of Turovskii imply the following extension of the famous result of de Pagter to semigroups. Let
be a multiplicative semigroup of quasinilpotent compact positive operators on a Banach lattice of dimension at least two. Then
has a common non-trivial invariant closed ideal.This work was supported by the Research Ministry of Slovenia. 相似文献
973.
Wlodzimierz Jelonek 《Proceedings of the American Mathematical Society》2001,129(1):247-256
The aim of this paper is to give a characterization of 3-K-contact and quasi 3-K-contact manifolds.
974.
Given H≥0 and bounded convex curves α1, ...,⇌n, α in the plane z=0 bounding domains D1, …, Dn, D, respectively, with
if i ∈ j and with Di ⊂ D, we obtain several results proving the existence of a constanth depending only on H and on the geometry of the curves
αi, α such that the Dirichlet problem for the constant mean curvature H equation:
where
may accept or not a solution. 相似文献
975.
Silvano Delladio 《Journal of Geometric Analysis》2001,11(1):17-42
We show that the L
p
norm of the second fundamental form of hypersurfaces in
R
n+1
is very coercive in the GMT setting of Gauss graphs currents, when p exceeds the dimension n. A compactness result for immersed
hypersurfaces and its application to a variational problem are provided. 相似文献
976.
Ferenc Móricz 《Journal of Fourier Analysis and Applications》2001,7(6):601-614
A theorem of Fejér states that if a periodic function F is of bounded variation on the closed interval [0, 2π], then the nth
partial sum of its formally differentiated Fourier series divided by n converges to π-1[F(x+0)-F(x-0)] at each point x. The generalization of this theorem for Fourier-Stieltjes series of (nonperiodic) functions of bounded variation
is also well known.
The aim of the present article is to extend these results to the (m, n)th rectangular partial sum of double Fourier or Fourier-Stieltjes
series of a function F(x, y) of bounded variation over the closed square [0, 2π]×[0, 2π] in the sense of Hardy and Krause.
As corollaries, we also obtain the following results:
相似文献
(i) | The terms of the Fourier or Fourier-Stieltjes series of F(x, y) determine the atoms of the (periodic) Borel measure induced by (an appropriate extension of) F. |
(ii) | In the case of periodic functions F(x, y) of bounded variation, the class of double Fourier-Stieltjes series coincides with the class of series that can be obtained from their Fourier series by a formal termwise differentiation with respect to both x and y. |
977.
Let P be a bounded analytic polyhedron in ℂ2 whose boundary is smooth except for normal crossing singularities. We show that P is a holomorphic quotient of the bidisc,
if its automorphism group is noncompact. 相似文献
978.
David E. Dobbs 《Rendiconti del Circolo Matematico di Palermo》2000,49(2):319-324
Résumé SoitR ⊂T une extension des anneaux commutatifs et soit {P
α :α ∈I} une cha?ne croissante des idéaux premiers deR (I étant un ensemble totalement ordonné, peut-être infini). Alors il existe un anneau de paravaluationV deT et une cha?ne {Q
α} des idéaux premiers deV de sorte queR ⊂V etQ
α ∩R =P
α pour toutα ∈I. Tout d’abord, on établit le cas spécial dans lequelT est un corps; dans ce cas, on trouve en effet un tel anneau de valuationV deT. Ensuite, l’assertion ci-dessus pour le cas général découle comme conséquence. Dans le cas général, on peut aussi remplacer
le mot “paravaluation” avec le mot “valuation” siR est un anneau de Marot etT est son anneau total de fractions.
相似文献
979.
Let be a Moran set associated with the set . Let Γ be a non-empty subset of with non-empty complement. Associated with the behaviour of success run of symbols from Γ in the coding space is a decomposition of F such that
Depending on F this might be a partition of F or almost a partition of F in the sense that . We prove that each F
t
is dense in F, and with . For -a.e. and F
t
is an s-set when . Moreover, associated with this decomposition of F is a measurable function Y such that each F
t
is a level set of Y. The fractal dimensions of the graph of Y are also determined.
(Received 17 January 2000; in revised form 13 July 2000) 相似文献
980.
We present an extensive analysis ofpositively quadratically hyponormal weighted shiftsW
with 0 = 1 = 1. Our main result states that such weighted shifts abound! Specifically, by focusing on recursively generated weighted shifts of the form, we establish that the planar set is positively quadratically hyponormal} is a closed convex, set with nonempty interior. In addition, we are able to describe in detail the boundary of
Research partially supported by NSF grants DMS-9401455 and DMS-9800931Research partially supported by KOSEF grant 971-0102-006-2 and by TGRC-KOSEF 相似文献