共查询到20条相似文献,搜索用时 31 毫秒
1.
Let be a finite separable extension, , and the torsion subgroup of . When is an abelian extension is explicitly determined. This information is used to study the structure of . In particular, when am = a ∈ F is explicitly determined. 相似文献
2.
Ep de Jonge 《Journal of Functional Analysis》1976,23(2):119-134
Under the condition that , (the set of singular functionals on a normed Köthe space Lθ) is an abstract L-space, it is proved in this paper that there exists a set of purely finitely additive measures θ such that ? holds. It follows that is an abstract L-space if and only if is Riesz isomorphic and isometric with a band in . 相似文献
3.
Rahman Younis 《Journal of Functional Analysis》1981,44(3):381-387
The main result of this paper is that if F is a closed subset of the unit circle, then is an M-ideal of . Consequently, if then ? has a closest element in H∞ + LF∞. Furthermore, if is not the dual of any Banach space. 相似文献
4.
We study generalizations of Ramsey theorem to systems of finite subsets of ω. A system of finite subsets of ω is called to be Ramsey if for every partition =1∪2 there exists an infinite set Y?ω such that . We give some sufficient conditions for a system to be Ramsey. We also prove a theorem which concerns partitions into infinitely many classes. This may be regarded as a common generalization of Erdös-Rado and Nash-Williams theorems. 相似文献
5.
The spaces in the title are associated to a fixed representing measure m for a fixed character on a uniform algebra. It is proved that the set of representing measures for that character which are absolutely continuous with respect to m is weakly relatively compact if and only if each m-negligible closed set in the maximal ideal space of L∞ is contained in an m-negligible peak set for H∞. J. Chaumat's characterization of weakly relatively compact subsets in therefore remains true, and is complete, under the first conditions. In this paper we also give a direct proof. From this we obtain that has the Dunford-Pettis property. 相似文献
6.
Juan C. Peral 《Journal of Functional Analysis》1980,36(1):114-145
Let u(x, t) be the solution of utt ? Δxu = 0 with initial conditions . Consider the linear operator . (Here g = 0.) We prove for t fixed the following result. Theorem 1: T is bounded in Lp if and only if . Theorem 2: If the coefficients are variables in C and constant outside of some compact set we get: (a) If n = 2k the result holds for . (b) If n = 2k ? 1, the result is valid for . This result are sharp in the sense that for p such that we prove the existence of in such a way that . Several applications are given, one of them is to the study of the Klein-Gordon equation, the other to the completion of the study of the family of multipliers and finally we get that the convolution against the kernel is bounded in H1. 相似文献
7.
8.
《Journal of Functional Analysis》1987,75(1):58-91
The problem of prequantization of infinite dimensional dynamical systems is considered, using a Gaussian measure on an Abstract Wiener Space to play the role of volume element replacing the Liouville measure. As an example, it is shown that the flow on corresponding to the nonlinear Klein-Gordon field over a two dimensional static space time leaves the Gaussian measure defined on this space w.r.t. the norm on Ls + 12 × Ls2 (where quasi-invariant. This makes it possible to carry out the prequantization in this case. 相似文献
9.
For a finite lattice L, denote by and respectively the upper length and lower length of L. The grading number g(L) of L is defined as where Sub(L) is the sublattice-lattice of L. We show that if K is a proper homomorphic image of a distributive lattice L, then ; and derive from this result, formulae for and g(L) where L is a product of chains. 相似文献
10.
In this Note we give a generalization of Hardy's theorem for the Dunkl transform on . More precisely, for all a>0, b>0 and p,q∈[1,+∞], we determine the measurable functions f such that and , where are the Lp spaces associated with the Dunkl transform. To cite this article: L. Gallardo, K. Trimèche, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 849–854. 相似文献
11.
The main result is the following. Let be a bounded Lipschitz domain in , d?2. Then for every with ∫f=0, there exists a solution of the equation divu=f in , satisfying in addition u=0 on and the estimate where C depends only on . However one cannot choose u depending linearly on f. To cite this article: J. Bourgain, H. Brezis, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 973–976. 相似文献
12.
Itaru Mitoma 《Journal of Functional Analysis》1985,61(3):342-359
On a modified space Φ′ from the space ′ of tempered distributions, it is proven that a stochastic equation, , has a unique solution, where W(t) is a Φ′-valued Brownian motion independent of a Φ′-valued Gaussian random variable γ and is an integro-differential operator. As an application, a fluctuaton result (or central limit theorem) is shown for interacting diffusions. 相似文献
13.
Norbert Wielens 《Journal of Functional Analysis》1985,61(1):98-115
A necessary and sufficient condition is given for the generalized Schrödinger operator to be essentially self-adjoint in , under general assumptions on ? and for arbitrary domains Ω in n. In particular, if ? is strictly positive and locally Lipschitz continuous on , then A is essentially. self-adjoint. Examples of non-essential self-adjointness and a complete discussion of the one-dimensional case are also given. These results have applications to the problem of the essential self-adjointness of quantum Hamiltonians and to the uniqueness problem of Markov processes. 相似文献
14.
Elliptic operators , α a multi-index, with leading term positive and constant coefficient, and with lower order coefficients defined on or a quotient space are considered. It is shown that the Lp-spectrum of A is contained in a “parabolic region” Ω of the complex plane enclosing the positive real axis, uniformly in p. Outside Ω, the kernel of the resolvent of A is shown to be uniformly bounded by an L1 radial convolution kernel. Some consequences are: A can be closed in all Lp (1 ? p ? ∞), and is essentially self-adjoint in L2 if it is symmetric; A generates an analytic semigroup e?tA in the right half plane, strongly Lp and pointwise continuous at t = 0. A priori estimates relating the leading term and remainder are obtained, and summability , with φ analytic, is proved for , with convergence in Lp and on the Lebesgue set of ?. More comprehensive summability results are obtained when A has constant coefficients. 相似文献
15.
L.R. Haff 《Journal of multivariate analysis》1977,7(3):374-385
Let Sp×p ~ Wishart (Σ, k), Σ unknown, k > p + 1. Minimax estimators of Σ?1 are given for L1, an Empirical Bayes loss function; and L2, a standard loss function (Ri ≡ E(Li ∣ Σ), i = 1, 2). The estimators are , a, b ≥ 0, r(·) a functional on . Stein, Efron, and Morris studied the special cases and , for certain, a, b. From their work , a = k ? p ? 1, b = p2 + p ? 2; whereas, we prove . The reversal is surprising because a.e. (for a particular L2). Assume (compact) ? , the set of p × p p.s.d. matrices. A “divergence theorem” on functions Fp×p : → implies identities for Ri, i = 1, 2. Then, conditions are given for , i = 1, 2. Most of our results concern estimators with r(S) = t(U)/tr(S), U = p ∣S∣1/p/tr(S). 相似文献
16.
We give several characterizations of those Banach spaces X such that the dual contains a complemented subspace isomorphic to . We investigate operators on separable ∞ spaces whose adjoints have nonseparable ranges and apply our results to obtain a structure theorem for ∞ spaces whose duals are not isomorphic to l1(Γ). 相似文献
17.
The problem under consideration is to schedule jobs on a machine in order to minimize the sum of the penalties of delayed jobs. A “range-and-bound” method is proposed for finding a tight bound P? such that P?≤P1≤2P?, P1 being the minimal sum desired. The considered scheduling problem, for n jobs and accuracy ε > 0, is solved by a fully polynomial ε-approximation algorithm in time and space. 相似文献
18.
J.W Jenkins 《Journal of Functional Analysis》1979,32(2):131-138
Let N denote a connected, simply connected nilpotent Lie group with discrete cocompact subgroup Γ. Let U denote the quasi-regular representation on N on . can be written as a direct sum of primary subspaces with respect to U. A realization for the projections of ) onto these primary summands is given in this paper. 相似文献
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20.
Let be a smooth second order differential operator on n written in Hörmander form, and be a bounded open set with smooth noncharacteristic boundary. Under a global condition that ensures that the Dirichlet problem is well posed for L on and a nondegeneracy condition at the boundary (precisely: the Lie algebra generated by the vector fields V0, V1,…, Vd is of full rank on the boundary) then the harmonic measure for L starting at any point in has a smooth density with respect to the natural boundary measure. Estimates on the derivatives of this density (the Poisson kernel) similar to the classical estimates for the Poisson kernel for the Laplacian on a half space are given. 相似文献