共查询到20条相似文献,搜索用时 15 毫秒
1.
Dorina Mitrea 《Integral Equations and Operator Theory》1997,29(3):320-338
In this paper we discuss the solvability of boundary value problems for the Laplace operator on Lipschitz domains with arbitrary topology via boundary layers. An application to hydrodynamics is included.Partially supported by a UMC Research Board grant and UMC Summer Research Fellowship 相似文献
2.
Liming Yang 《Integral Equations and Operator Theory》1996,25(3):373-376
Let 1<p< and
. LetC
q
denote the Bessel capacity in the plane. Let
be the set of homomorphisms ofH
(G) such that (z)= and letNP denote the set of points in G for which
is not a peak set forH
(G). In this note, we show that ifC
q
(NP)=0, thenH
(G) is dense inL
a
p
(G), the Bergman space overG.Partially supported by NSF DMS-9401234 相似文献
3.
In this paper, we have proven that for the Jordan blockS() withS() (SI),
i=1
n
S() =S()
(n)
(n 1) has unique finite (SI) decomposition up to a similarity. As result, we obtain that ifV is a Volterra operator onH=L
2([0, 1]), thenV
(n)
has unique finite (SI) decomposition.This project was supported by National Natural Science Foundation of China. 相似文献
4.
We introduce constraint-based scheduling and discuss its main principles. An approximation algorithm based on tree search is developed for the job shop scheduling problem using ILOG SCHEDULER. A new way of calculating lower bounds on the makespan of the job shop scheduling problem is presented and we show how such results can be used within a constraint-based approach. An empirical performance analysis shows that the algorithm we developed performs well. Finally, taking the job shop scheduling problem as a start point, we discuss how constraint-based scheduling can be used to solve more general scheduling problems. 相似文献
5.
M. C. Bartholomew-Biggs 《Journal of Optimization Theory and Applications》1993,78(2):393-399
This paper describes a procedure for computing accurate scalar products of real-valued vectors. Anada implementation of this procedure is used to demonstrate the extent to which the technique can improve the convergence of the conjugate gradient algorithm. We also give a brief discussion of the costs and limitations of accurate arithmetic operations. 相似文献
6.
Tobin A. Driscoll Folkmar Bornemann Lloyd N. Trefethen 《BIT Numerical Mathematics》2008,48(4):701-723
In Matlab, it would be good to be able to solve a linear differential equation by typing u = L\f, where f, u, and L are representations
of the right-hand side, the solution, and the differential operator with boundary conditions. Similarly it would be good to
be able to exponentiate an operator with expm(L) or determine eigenvalues and eigenfunctions with eigs(L). A system is described
in which such calculations are indeed possible, at least in one space dimension, based on the previously developed chebfun
system in object-oriented Matlab. The algorithms involved amount to spectral collocation methods on Chebyshev grids of automatically determined resolution.
AMS subject classification (2000) 65L10, 65M70, 65N35 相似文献
7.
A vector valued transference of Fourier-Bessel multipliers onto Hankel multipliers with applications
Jorge J. Betancor Krzysztof Stempak 《Rendiconti del Circolo Matematico di Palermo》2002,51(1):199-206
In this note we prove a vector valued transference theorem relating Fourier-Bessel multipliers and Hankel multipliers. An
application of such a transference theorem allows to show that results of Córdoba [3] and Romera [4] can be deduced from a
recent result of Balodis and Córdoba [1, Theorem 3].
Partially supported by DGICYT Grant PB 97-1489 (Spain).
Partially supported by KBN grant # 2 PO3A 034 20. 相似文献
8.
Peter B. Gilkey 《Journal of Geometric Analysis》1994,4(2):155-158
Osserman conjectured that if the curvature operatorR of a Riemannian manifoldM has constant eigenvalues, thenM is locally a rank-1 symmetric space or is flat. The pointwise question is considerably more complicated. We present examples
of Riemannian manifolds so thatR has constant eigenvalues at the basepoint, butR is not the curvature operator of a rank-1 symmetric space.
Research partially supported by the NSF and IHES. 相似文献
9.
In this paper we introduce a weighted Cheeger constant and show that the gap between the first two eigenvalues of a Riemannian
manifold given Dirichlet conditions can be bounded from below in terms of this constant. When the Riemannian manifold is a
bounded Euclidean domain satisfying an interior rolling sphere condition we give an estimate on the weighted Cheeger constant
in terms of the rolling sphere radius, volume, a bound on the principal curvatures of the boundary and the dimension. This
yields a lower bound on the nontrivial gap for Euclidean domains.
S-Y. Cheng’s research partially supported by the CUHK direct grant A/C # 220600260. K. Oden’s research partially supported
by the Department of Education Graduate Fellowship 相似文献
10.
Gábor Czédli 《Algebra Universalis》2009,60(1):107-124
We introduce definitions of semifractal, 0–1-fractal, quasifractal and fractal lattices. A variety generated by a fractal lattice is called fractal generated, with analogous terminology for the other variants.
We show that a semifractal generated nondistributive lattice variety cannot be of residually finite length. This easily implies
that there are exactly continuously many lattice varieties which are not semifractal generated. On the other hand, for each
prime field F, the variety generated by all subspace lattices of vector spaces over F is shown to be fractal generated. These countably many varieties and the class of all distributive lattices are the only known fractal generated lattice varieties at present. Four distinct countable distributive
fractal lattices are given each of which generates . After showing that each lattice can be embedded in a quasifractal, continuously many quasifractals are given each of which
has cardinality and generates the variety of all lattices.
Semifractal considerations are applied to construct examples of convexities that include no minimal convexity, thus answering
a question of Jakubík. (A convexity is a class of lattices closed under taking homomorphic images, convex sublattices and direct products, a notion due to Ervin
Fried.)
This research was partially supported by the NFSR of Hungary (OTKA), grant no. T 049433 and K 60148. 相似文献
11.
For a large class of metric spaces with nice local structure, which includes Banach–Finsler manifolds and geodesic spaces
of curvature bounded above, we give sufficient conditions for a local homeomorphism to be a covering projection. We first
obtain a general condition in terms of a path continuation property. As a consequence, we deduce several conditions in terms
of path- liftings involving a generalized derivative, and in particular we obtain an extension of Hadamard global inversion
theorem in this context. Next we prove that, in the case of quasi-isometric mappings, some of these sufficient conditions
are also necessary. Finally, we give an application to the existence of global implicit functions.
O. Gutú and J. A. Jaramillo were supported in part by D.G.E.S. (Spain) Grant BFM2003-06420. 相似文献
12.
We construct pairs of conformally equivalent isospectral Riemannian metrics ?1g and ?2g on spheres Sn and balls Bn+1 for certain dimensions n, the smallest of which is n=7, and on certain compact simple Lie groups. In the case of Lie groups, the metric g is left-invariant. In the case of spheres and balls, the metric g not the standard metric but may be chosen arbitrarily close to the standard one. For the same manifolds (M, g) we also show that the functions ?1 and ?2 are isospectral potentials for the Schrödinger operator ?2\gD + \gf. To our knowledge, these are the first examples of isospectral potentials and of isospectral conformally equivalent metrics on simply connected closed manifolds. 相似文献
13.
Nicolas G. Fournier 《Journal of Heuristics》2007,13(6):587-639
A new analytical tool is presented to provide a better understanding of the search space of k-sat. This tool, termed the local value distribution , describes the probability of finding assignments of any value q′ in the neighbourhood of assignments of value q. The local value distribution is then used to define a Markov model to model the dynamics of a corresponding stochastic local
search algorithm for k-sat. The model is evaluated by comparing the predicted algorithm dynamics to experimental results. In most cases the fit of the
model to the experimental results is very good, but limitations are also recognised. 相似文献
14.
If the unit sphere of a Banach space X can be covered by countably many balls no one of which contains the origin, then, as an easy consequence of the separation
theorem, X* is w*-separable. We prove the converse under suitable renorming. Moreover, the balls of the countable covering can be chosen as
translates of the same ball.
Research of V. P. Fonf was supported in part by Israel Science Foundation, Grant # 139/02 and by the Istituto Nazionale di
Alta Matematica of Italy. Research of C. Zanco was supported in part by the Ministero dell’Università e della Ricerca Scientifica
e Tecnologica of Italy and by the Center for Advanced Studies in Mathematics at the Ben-Gurion University of the Negev, Beer-Sheva,
Israel. 相似文献
15.
Suppose thatM n is a complete, noncompact, Riemannian manifold. If Δ denotes the Laplace operator ofM, one has associated Schrödinger operators ? Δ +V. Conditions onV are formulated, which ensures the essential self-adjointness of ? Δ +V. In particular, ifV ∈ Qα,loc (M n), the local Stummel class, andV ≥ ? c outside of a compact set, then ? Δ +V is essentially self-adjoint on C 0 ∞ (M n). In addition, essential self-adjointness is proved for potentials which are strongly singular at a point. The absence of eigenvalues of ?Δ +V is also studied. This relies upon Rellich-type identities. The results on strongly singular potentials make use of a generalization of the classical uncertainty principle, inR n, to Riemannian manifolds with a pole. 相似文献
16.
Quo-Shin Chi 《Journal of Geometric Analysis》1991,1(4):373-382
It is proved that if the Besicovitch Covering Lemma is true on either a Hadamard manifold or a simply connected surface without
focal points that covers a compact quotient, then the manifold is the Euclidean space. As a corollary, the vanishing of the
topological entropy of a compact manifold of nonpositive curvature or of a compact surface without focal points is equivalent
to the validity of the Besicovitch Covering Lemma on the universal covering space of the manifold.
The author was partially supported by an NSF grant. 相似文献
17.
Fengping Yao 《Archiv der Mathematik》2009,92(2):137-146
In this paper we give a new proof for Lp estimates of the Calderón-Zygmund type singular integrals. Our approach is completely free from harmonic analysis.
This work was partially supported by the innovation foundation of Shanghai university under
Grant A10-0101-08-905. 相似文献
18.
We prove that, on a complete noncompact Riemannian manifold with bounded geometry, the Lp boundedness of the Riesz transform, for p>2, is stable under a quasi-isometric and integrable change of metric. As an intermediate
step, we treat the case of weighted divergence form operators in the Euclidean space. 相似文献
19.
Jiaping Wang 《Journal of Geometric Analysis》1998,8(3):485-514
We consider the existence, uniqueness and convergence for the long time solution to the harmonic map heat equation between
two complete noncompact Riemannian manifolds, where the target manifold is assumed to have nonpositive curvature. As an application,
we solve the Dirichlet problem at infinity for proper harmonic maps between two hyperbolic manifolds for a class of boundary
maps. The boundary map under consideration has finite many points at which either it is not differentiable or has vanishing
energy density. 相似文献
20.
L. Brandolini G. Gigante A. Greenleaf A. Iosevich A. Seeger G. Travaglini 《Journal of Geometric Analysis》2007,17(1):15-40
We consider Fourier transforms
of densities supported on curves in ℝd. We obtain sharp lower and close to sharp upper bounds for the decay rates of
as R → ∞. 相似文献