共查询到20条相似文献,搜索用时 15 毫秒
1.
Let be an ideal. We say that a sequence of real numbers is -convergent to if for every neighborhood U of y the set of n's satisfying ynU is in . Basing upon this notion we define pointwise -convergence and -convergence in measure of sequences of measurable functions defined on a measure space with finite measure. We discuss the relationship between these two convergences. In particular we show that for a wide class of ideals including Erdős–Ulam ideals and summable ideals the pointwise -convergence implies the -convergence in measure. We also present examples of very regular ideals such that this implication does not hold. 相似文献
2.
Norman L. Johnson Giuseppe Marino Olga Polverino Rocco Trombetti 《Finite Fields and Their Applications》2008,14(2):456-469
In [G. Marino, O. Polverino, R. Trombetti, On -linear sets of PG(3,q3) and semifields, J. Combin. Theory Ser. A 114 (5) (2007) 769–788] it has been proven that there exist six non-isotopic families (i=0,…,5) of semifields of order q6 with left nucleus and center , according to the different geometric configurations of the associated -linear sets. In this paper we first prove that any semifield of order q6 with left nucleus , right and middle nuclei and center is isotopic to a cyclic semifield. Then, we focus on the family by proving that it can be partitioned into three further non-isotopic families: , , and we show that any semifield of order q6 with left nucleus , right and middle nuclei and center belongs to the family . 相似文献
3.
Ju Myung Kim 《Journal of Mathematical Analysis and Applications》2006,320(2):619-631
This paper is concerned with compactness for some topologies on the collection of bounded linear operators on Banach spaces. New versions of the Eberlein–Šmulian theorem and Day's lemma in the collection are established. Also we obtain a partial solution of the dual problem for the quasi approximation property, that is, it is shown that for a Banach space X if X** is separable and X* has the quasi approximation property, then X has the quasi approximation property. 相似文献
4.
Dalibor Volný Benjamin Weiss 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2004,40(6):771-778
Let T be an ergodic automorphism of a probability space, f a bounded measurable function, . It is shown that the property that the probabilities μ(|Sn(f)|>n) are of order n−p roughly corresponds to the existence of an approximation in L∞ of f by functions (coboundaries) g−g○T, gLp. Similarly, the probabilities μ(|Sn(f)|>n) are exponentially small iff f can be approximated by coboundaries g−g○T where g have finite exponential moments.
Résumé
Soit T un automorphisme ergodique d'un espace probabilisé, f une fonction bornée mesurable et . Une correspondance est établie entre l'existence de l'estimation des probabilités μ(|Sn(f)|>n) d'ordre n−p et l'existence de l'approximation dans L∞ de la fonction f par des cobords g−g○T où g est “presque” dans Lp. De manière similaire, les probabilités μ(|Sn(f)|>n) sont d'ordre e−cn, pour un certain c>0, n=1,2… , si et seulement si f admet une approximation dans L∞ par des cobords g−g○T avec g ayant des moments exponentiels. 相似文献5.
6.
Changxing Miao Guixiang Xu Lifeng Zhao 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2009,26(5):1831-1852
We prove the global well-posedness and scattering for the defocusing -subcritical (that is, 2<γ<3) Hartree equation with low regularity data in , d3. Precisely, we show that a unique and global solution exists for initial data in the Sobolev space with s>4(γ−2)/(3γ−4), which also scatters in both time directions. This improves the result in [M. Chae, S. Hong, J. Kim, C.W. Yang, Scattering theory below energy for a class of Hartree type equations, Comm. Partial Differential Equations 33 (2008) 321–348], where the global well-posedness was established for any s>max(1/2,4(γ−2)/(3γ−4)). The new ingredients in our proof are that we make use of an interaction Morawetz estimate for the smoothed out solution Iu, instead of an interaction Morawetz estimate for the solution u, and that we make careful analysis of the monotonicity property of the multiplier m(ξ)ξp. As a byproduct of our proof, we obtain that the Hs norm of the solution obeys the uniform-in-time bounds. 相似文献
7.
The solution of the linear operator equation:An-1X+An-2XB++AXBn-2+XBn-1=Y is given by if the spectra of A and B are in the sector {z:z≠0,-π/n<argz<π/n}. 相似文献
8.
Our aim in this paper is to investigate the global asymptotic stability of all positive solutions of the higher order nonlinear difference equationwhere B, C and α, β, γ are positive, k {1, 2, 3, … }, and the initial conditions x−2k+1, … , x−1, x0 are positive real numbers. We show that the unique positive equilibrium of the equation is globally asymptotically stable and has some basins that depend on certain conditions posed on the coefficients. Our concentration is on invariant intervals, the character of semicycles, and the boundedness of the above mentioned equation. Our final comments are about informative examples. 相似文献
9.
As a natural generalization of fuzzy metric spaces due to George and Veeramani [George A, Veeramani P. On some result in fuzzy metric space. Fuzzy Sets Syst 1994;64:395–9], the present author defined the notion of -fuzzy metric spaces. In this paper we prove some known results of metric spaces including Uniform continuity theorem and Ascoli–Arzela theorem for -fuzzy metric spaces. We also prove that every -fuzzy metric space has a countably locally finite basis and use this result to conclude that every -fuzzy metric space is metrizable. 相似文献
10.
The extension field where q is a prime divisor of (P−1), has a unique structure. This paper describes this unique structure and uses it to derive formulas relating the trace values for elements in . These formulas can be refined for certain elements to produce a formula for the trace. 相似文献
11.
In this paper, first we define and study the probabilistic n-normed spaces and -n-compactness, also we prove some theorems and inequalities. In the next section we define -n-boundedness and prove some results in relation between -n-compact and -n-bounded sets in these spaces. 相似文献
12.
Let k be an algebraically closed field of characteristic 2. We prove that the restricted nilpotent commuting variety , that is the set of pairs of (n×n)-matrices (A,B) such that A2=B2=[A,B]=0, is equidimensional. can be identified with the ‘variety of n-dimensional modules’ for , or equivalently, for k[X,Y]/(X2,Y2). On the other hand, we provide an example showing that the restricted nilpotent commuting variety is not equidimensional for fields of characteristic >2. We also prove that if e2=0 then the set of elements of the centralizer of e whose square is zero is equidimensional. Finally, we express each irreducible component of as a direct sum of indecomposable components of varieties of -modules. 相似文献
13.
In a previous paper we characterized unilevel block α-circulants , , 0mn-1, in terms of the discrete Fourier transform of , defined by . We showed that most theoretical and computational problems concerning A can be conveniently studied in terms of corresponding problems concerning the Fourier coefficients F0,F1,…,Fn-1 individually. In this paper we show that analogous results hold for (k+1)-level matrices, where the first k levels have block circulant structure and the entries at the (k+1)-st level are unstructured rectangular matrices. 相似文献
14.
Ai-Guo Wu Hao-Qian Wang Guang-Ren Duan 《Journal of Computational and Applied Mathematics》2009,230(2):690-698
With the help of the concept of Kronecker map, an explicit solution for the matrix equation X−AXF=C is established. This solution is neatly expressed by a symmetric operator matrix, a controllability matrix and an observability matrix. In addition, the matrix equation is also studied. An explicit solution for this matrix equation is also proposed by means of the real representation of a complex matrix. This solution is neatly expressed by a symmetric operator matrix, two controllability matrices and two observability matrices. 相似文献
15.
R 《Advances in Mathematics》2009,220(6):1842-1922
For each p>n we use local oscillations and doubling measures to give intrinsic characterizations of the restriction of the Sobolev space to an arbitrary closed subset of Rn. 相似文献
16.
For all integers m3 and all natural numbers a1,a2,…,am−1, let n=R(a1,a2,…,am−1) represent the least integer such that for every 2-coloring of the set {1,2,…,n} there exists a monochromatic solution to
a1x1+a2x2++am−1xm−1=xm.