排序方式: 共有16条查询结果,搜索用时 31 毫秒
1.
Libor Veselý 《Czechoslovak Mathematical Journal》2002,52(4):721-729
We give a full characterization of the closed one-codimensional subspaces of c
0, in which every bounded set has a Chebyshev center. It turns out that one can consider equivalently only finite sets (even only three-point sets) in our case, but not in general. Such hyperplanes are exactly those which are either proximinal or norm-one complemented. 相似文献
2.
G. Sankara Raju Kosuru P. Veeramani 《Numerical Functional Analysis & Optimization》2013,34(7):821-830
We introduce a notion of pointwise cyclic contraction T satisfying TA ? B and TB ? A to obtain the existence of a point x ∈ A, such that d(x, Tx) = dist(A, B), known as a best proximity point for such a map. We also prove that for any x ∈ A, the Picard iteration {T2nx} converges to a best proximity point. 相似文献
3.
SizweMabizela 《分析论及其应用》2003,19(2):121-129
Let (X,d) be a real metric linear space, with translation-invariant metric d and G a linear subspace of X. In this paper we use functionals in the Lipschitz dual of X to characterize those elements of G which are best approximations to elements of X. We also give simultaneous characterization of elements of best approximation and also consider elements of ε-approximation. 相似文献
4.
Sh. Rezapour 《分析论及其应用》2006,22(2):114-119
In 1965 Ga¨hler introduced 2-normed spaces and since then, this topic have been intensively studied and developed. We shall introduce the notion of 1-type proximinal subspaces of 2-normed spaces and give some results in this field. 相似文献
6.
M.R.Haddadi 《分析论及其应用》2014,30(4):399-404
In this paper, we give some result on the simultaneous proximinal subset and simultaneous Chebyshev in the uniformly convex Banach space. Also we give relation between fixed point theory and simultaneous proximity. 相似文献
7.
H. Mohebi A. M. Rubinov 《分析论及其应用》2006,22(1):20-40
We develop a theory of downward sets for a class of normed ordered spaces. We study best approximation in a normed ordered space X by elements of downward sets, and give necessary and sufficient conditions for any element of best approximation by a closed downward subset of X. We also characterize strictly downward subsets of X, and prove that a downward subset of X is strictly downward if and only if each its boundary point is Chebyshev. The results obtained are used for examination of some Chebyshev pairs (W,x), where ∈ X and W is a closed downward subset of X 相似文献
8.
Let X be a Banach space, S be a compact Hausdorff space and Y be a U-proximinal subspace of X. We prove that C(S,Y) is locally uniformly strongly proximinal in C(S,X) and the corresponding metric projection map is Hausdorff metric continuous. 相似文献
9.
T. S. S. R. K. Rao 《Proceedings Mathematical Sciences》1999,109(3):309-315
In this note we consider the property of being constrained in the bidual, for the space of Bochner integrable functions. For
a Banach spaceX having the Radon-Nikodym property and constrained in its bidual and forY ⊂ X, under a natural assumption onY, we show thatL
1 (μ, X/Y) is constrained in its bidual andL
1 (μ, Y) is a proximinal subspace ofL
1(μ, X). As an application of these results, we show that, ifL
1(μ, X) admits generalized centers for finite sets and ifY ⊂ X is reflexive, thenL
1
μ, X/Y) also admits generalized centers for finite sets. 相似文献
10.
Darapaneni Narayana 《Proceedings of the American Mathematical Society》2006,134(4):1167-1172
We characterize finite-dimensional normed linear spaces as strongly proximinal subspaces in all their superspaces. A connection between upper Hausdorff semi-continuity of metric projection and finite dimensionality of subspace is given.