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GENERALIZATIONS OF THE SUZUKI AND KANNAN FIXED POINT THEOREMS IN G-CONE METRIC SPACES 被引量:1
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作者 mohammad sadegh asgari Zohreh Abbasbigi 《Analysis in Theory and Applications》 2012年第3期248-262,共15页
In this paper we develop the Banach contraction principle and Kannan fixed point theorem on generalized cone metric spaces. We prove a version of Suzuki and Kannan type generalizations of fixed point theorems in gener... In this paper we develop the Banach contraction principle and Kannan fixed point theorem on generalized cone metric spaces. We prove a version of Suzuki and Kannan type generalizations of fixed point theorems in generalized cone metric spaces. 展开更多
关键词 fixed point D-metric space 2-metric space generalized cone metric space Kannan mapping generalized Kannan mapping contractive mapping
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ON THE STABILITY OF FUSION FRAMES (FRAMES OF SUBSPACES)
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作者 mohammad sadegh asgari 《Acta Mathematica Scientia》 SCIE CSCD 2011年第4期1633-1642,共10页
A frame is an orthonormal basis-like collection of vectors in a Hilbert space, but need not be a basis or orthonormal. A fusion frame (frame of subspaces) is a frame-like collection of subspaces in a Hilbert space, ... A frame is an orthonormal basis-like collection of vectors in a Hilbert space, but need not be a basis or orthonormal. A fusion frame (frame of subspaces) is a frame-like collection of subspaces in a Hilbert space, thereby constructing a frame for the whole space by joining sequences of frames for subspaces. Moreover the notion of fusion frames provide a framework for applications and providing efficient and robust information processing algorithms.In this paper we study the conditions under which removing an element from a fusion frame, again we obtain another fusion frame. We give another proof of [5, Corollary 3.3(iii)] with extra information about the bounds. 展开更多
关键词 fusion frames (frames of subspaces) exact fusion frame dual fusion frames
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New Characterizations of Operator-Valued Bases on Hilbert Spaces
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作者 mohammad sadegh asgari 《Analysis in Theory and Applications》 CSCD 2017年第2期157-177,共21页
In this paper we study operator valued bases on Hilbert spaces and similar to Schauder bases theory we introduce characterizations of this generalized bases in Hilbert spaces. We redefine the dual basis associated wit... In this paper we study operator valued bases on Hilbert spaces and similar to Schauder bases theory we introduce characterizations of this generalized bases in Hilbert spaces. We redefine the dual basis associated with a generalized basis and prove that the operators of a dual g-basis are continuous. Finally we consider the stability of g-bases under small perturbations. We generalize two results of Krein- Milman-Rutman and Paley-Wiener [7] to the situation of g-basis. 展开更多
关键词 g-bases dual g-bases g-biorthogonal sequence.
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On the Generality of Orthogonal Projections and e-Projections in Banach Algebras
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作者 mohammad sadegh asgari Seyedeh Sara Karimizad Hamidreza Rahimi 《Advances in Pure Mathematics》 2012年第5期318-322,共5页
In this paper we develop the orthogonal projections and e-projections in Banach algebras. We prove some necessary and sufficient conditions for them and their spectrums. We also show that the sum of two generalized or... In this paper we develop the orthogonal projections and e-projections in Banach algebras. We prove some necessary and sufficient conditions for them and their spectrums. We also show that the sum of two generalized orthogonal projections u and v is a generalized orthogonal projection if, uv=vu=0. Our results generalize the results obtained for bounded linear operators on Hilbert spaces. 展开更多
关键词 GENERALIZED ORTHOGONAL PROJECTION ORTHOGONAL PROJECTION GENERALIZED e-Projection e-Projection
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