共查询到20条相似文献,搜索用时 46 毫秒
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Raffaella Cilia Joaquín M. Gutirrez 《Journal of Mathematical Analysis and Applications》2009,360(2):609-623
It is well known that a (linear) operator between Banach spaces is completely continuous if and only if its adjoint takes bounded subsets of Y* into uniformly completely continuous subsets, often called (L)-subsets, of X*. We give similar results for differentiable mappings. More precisely, if UX is an open convex subset, let be a differentiable mapping whose derivative is uniformly continuous on U-bounded subsets. We prove that f takes weak Cauchy U-bounded sequences into convergent sequences if and only if f′ takes Rosenthal U-bounded subsets of U into uniformly completely continuous subsets of . As a consequence, we extend a result of P. Hájek and answer a question raised by R. Deville and E. Matheron. We derive differentiable characterizations of Banach spaces not containing ℓ1 and of Banach spaces without the Schur property containing a copy of ℓ1. Analogous results are given for differentiable mappings taking weakly convergent U-bounded sequences into convergent sequences. Finally, we show that if X has the hereditary Dunford–Pettis property, then every differentiable function as above is locally weakly sequentially continuous. 相似文献
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《Mathematical and Computer Modelling》1998,27(5):1-14
Some fixed-point theorems are established for weakly contractive operators. These results will then be used to establish existence principles for functional, differential, and integral equations. 相似文献
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Summary We discuss the relationship between two different sequential connectedness, and prove that sequential connectedness is countably
multiplicative. 相似文献
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Anar Adiloglu Nabiev Ekrem Savas Mehmet Gürdal 《Journal of Applied Analysis & Computation》2019,9(2):739-746
In this paper we have introduced the statistically localized sequences in metric spaces and investigate basic properties of the statistically localized sequences. Also we have obtained some necessary and sufficient conditions for a localized sequence to be a statistically Cauchy sequence. It is also defined uniformly statistically localized sequences on metric spaces and its relation with statistically Cauchy sequences has been investigated. 相似文献
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Statistically convergent difference double sequence spaces 总被引:1,自引:0,他引:1
In this article we define the notion of statistically convergent difference double sequence spaces. We examine the spaces 2l∞(△, q), 2c(△, q), 2cB(△, q), 2cR(△, q), 2cBR(△,q) etc. being symmetric, solid, monotone, etc. We prove some inclusion results too. 相似文献
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Ya. A. Kofner 《Mathematical Notes》1973,14(5):967-972
Main results: A pseudostratifiable symmetrizable space possesses a symmetric with weak Cauchy condition. A space is strongly symmetrizable if and only if it is a pseudo-open II-image of a metric space. There exists a zero-dimensional symmetrizable space without a symmetric with weak Cauchy condition.All spaces satisfy the axiom T1.Translated from Matematicheskie Zametki, Vol. 14, No. 5, pp. 713–722, November, 1973. 相似文献
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Let X be a compactum and G an upper semi-continuous decomposition of X such that each element of G is the continuous image of an ordered compactum. If the quotient space X/G is the continuous image of an ordered compactum, under what conditions is X also the continuous image of an ordered compactum? Examples around the (non-metric) Hahn-Mazurkiewicz Theorem show that one must place severe conditions on G if one wishes to obtain positive results. We prove that the compactum X is the image of an ordered compactum when each g∈G has 0-dimensional boundary. We also consider the case when G has only countably many non-degenerate elements. These results extend earlier work of the first named author in a number of ways. 相似文献
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As a counterpart to best approximation in normed linear spaces, best coapproximation was introduced by Franchetti and Furi. In this paper, we apply the above coapproximation, and obtain some results on the upper semi-continuity of cometric projection maps. Also we shall determine under what conditions coproximinality can be transmitted to and from quotient spaces. 相似文献