共查询到20条相似文献,搜索用时 15 毫秒
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A. D. Baranov 《Proceedings of the American Mathematical Society》2006,134(10):3003-3013
We study boundedness of the differentiation and embedding operators in the shift-coinvariant subspaces generated by Blaschke products with sparse zeros, that is, in the spaces of meromorphic functions with fixed poles in the lower half-plane endowed with -norm. We answer negatively the question of K.M. Dyakonov about the necessity of the condition for the boundedness of the differentiation on . Our main tool is a construction of an unconditional basis of rational fractions in .
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假定T_σ是关于乘子σ的双线性Fourier乘子算子,其中σ满足如下Sobolev正则条件:对某个s∈(n,2n],有sup_(κ∈Z)‖σ_k‖W~s(R~(2m))∞.对于p_1,p_2,p∈(1,∞)且满足1/p=1/p_1+1/p_2和ω=(ω_1,ω_2)∈A_(p/t)(R~(2n)),建立了T_σ及其与函数b=(b_1,b_2)∈(BMO(R~n))~2生成的交换子T_(σ,b)由L~(p_1,λ)(ω_1)×L~(p_2,λ)(ω_2)到L~(p,λ)(v_w)的有界性;同时,在b_1,b_2∈CMO(R~n)(C_c~∞(R~n)在BMO拓扑下的闭包)的条件下,证明交换子T_(σ,b)是L~(p_1,λ)(ω_1)×L~(p_2,λ)(ω_2)到L~(p,λ)(v_w)的紧算子.为了得到主要结果,我们先后建立了几个双(次)线性极大函数在加多权Morrey空间上的有界性以及该空间中准紧集的判定. 相似文献
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本文运用算子理论方法,讨论了Hilbert空间H中的子空间框架和子空间框架算子的性质,研究了子空间框架的摄动,给出了一些有意义的结果. 相似文献
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Consider two types of translation-invariant functionals and on , and a sequence of functions fn whose corresponding symmetric rearrangements are convergent. We show that fn themselves converge up to translations if either or . These compactness results lead to applications in variational problems and stability problems in stellar dynamics. 相似文献
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In this paper,two concepts of relative compactness-the relative strong fuzzy compactness and the relative ultra-fuzzy compactness are defined in L-topological spaces for an arbitrary L-set.Properties of relative strong fuzzy sets and relative ultra-fuzzy compact sets are studied in detail and some characteristic theorems are given.Some examples are illustrated. 相似文献
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In this paper, the concept of degree of compactness is introduced in the general framework of I-fuzzy topological spaces, and its property is discussed. All good compactness are generalized to I-fuzzy topological spaces accordingly. 相似文献
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Let M and N be nonzero subspaces of a Hilbert space H, and PM and PN denote the orthogonal projections on M and N, respectively. In this note, an exact representation of the angle and the minimum gap of M and N is obtained. In addition, we study relations between the angle, the minimum gap of two subspaces M and N, and the reduced minimum modulus of (I - PN)PM, 相似文献
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Geng Zhibin 《大学数学》1998,(2)
本文研究了Banach空间的弱序列紧性.Banach空间X称为有(w)性质,如果X(X的共轭空间)的每个有界序列有弱收敛子列.我们证明了,如果Banach空间X有(w)性质,那么lp(X)(1≤p<+∞)与c0(X)也有(w)性质. 相似文献
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讨论了一维不可约强局部Dirichlet,型的正则子空间的Mosco收敛性.如果正则子空间的特征集是收敛的,那么相应的正则子空间在Mosco意义下也是收敛的.最后,用一些具体的例子说明了Mosco收敛不能保持Dirichlet型整体特性的稳定. 相似文献
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V. V. Shumilova 《Mathematical Notes》2006,79(1-2):224-231
We consider the compactness principle in the variable space L 2 related to a periodic Borel measure. It is assumed that the periodic Borel measure determines a periodic singular (i.e., irregular) or fine structure. We prove the compactness principle for the periodic singular and fine grids, box structures, and composite structures in the plane and in space. 相似文献
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Shaoguang Shi & Zunwei Fu 《分析论及其应用》2021,37(3):347-361
The more explicit decomposition of the operator and the kernel are utilized to investigate a characterization of the central $BMO(\mathbb{R}^{n})$-closure of $C_{c}^{\infty}(\mathbb{R}^{n})$ space via the compactness of the commutators of fractional Hardy operator with rough kernel. 相似文献
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In this paper, the notion of almost fuzzy compactness is defined in L-fuzzy topological spaces by means of inequality, where L is a completely distributive DeMorgan algebra. Its properties are discusse... 相似文献
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We continue the study of the variety X[M] of planar normal sections on a natural embedding of a flag manifold M. Here we consider those subvarieties of X[M] that are projective spaces. When M=G/T is the manifold of complete flags of a compact simple Lie group G, we obtain our main results. The first one characterizes those subspaces of the tangent space T[T] (M), invariant by the torus action and which give rise to real projective spaces in X[M]. The other one is the following. Let
be the tangent space of the inner symmetric space G/K at [K] . Then RP (
) is maximal in X[M] if and only if 2(G/K) does not vanish. 相似文献
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讨论了\Pi_1空间上一般JC*-代数的不变子空间的存在条件问题,得到各类JC*-代数存在\Pi_1型不变子空间的等价条件. 相似文献
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Gunther Jäger 《Fuzzy Sets and Systems》1997,90(3):737-348
Lowen and Lowen [Applications of category theory to fuzzy subsets (Kluwer, 1992) p. 153] and Lowen et al. [Fuzzy Sets and Systems 40 (1991) 347] recently introduced the category FCS of fuzzy convergence spaces, a topological quasitopos which is a supercategory of FTS, the category of fuzzy topological spaces. In this paper, compactness in FCS is examined. Doing so we found that to define compactness as an absolute property we had to generalize the definition of fuzzy convergence space to fuzzy subsets. All basic theorems are proved including the Tychonoff product theorem. Based on the theory developed here, in a following publication, a Richardson compactification for fuzzy convergence spaces will be given. 相似文献
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Jean-Paul Penot 《Set-Valued Analysis》1998,6(4):363-380
We study the local surjectivity and openness properties of mappings and correspondences by using coderivatives. We recall local criteria but concentrate on point criteria. Our study relies on a compactness condition which is of independent interest, for instance, for the study of the behavior of the injectivity constant of a linear map or of a convex process under stabilization procedures. Several known criteria for openness are shown to be a consequences of this new compactness condition. 相似文献