55 resultados para semigroup of bounded linear operators
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2000 Mathematics Subject Classification: 45F15, 45G10, 46B38.
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In this survey article we discuss some recent results concerning strong spectral estimates for Ruelle transfer operators for contact flows on basic sets similar to these of Dolgopyat obtained in the case of Anosov flows with C1 stable and unstable foliations. Some applications of Dolgopyat's results and the more recent ones are also described.
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AMS classification: 41A36, 41A10, 41A25, 41Al7.
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2000 Mathematics Subject Classification: Primary 47A48, Secondary 60G12.
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For a polish space M and a Banach space E let B1 (M, E) be the space of first Baire class functions from M to E, endowed with the pointwise weak topology. We study the compact subsets of B1 (M, E) and show that the fundamental results proved by Rosenthal, Bourgain, Fremlin, Talagrand and Godefroy, in case E = R, also hold true in the general case. For instance: a subset of B1 (M, E) is compact iff it is sequentially (resp. countably) compact, the convex hull of a compact bounded subset of B1 (M, E) is relatively compact, etc. We also show that our class includes Gulko compact. In the second part of the paper we examine under which conditions a bounded linear operator T : X ∗ → Y so that T |BX ∗ : (BX ∗ , w∗ ) → Y is a Baire-1 function, is a pointwise limit of a sequence (Tn ) of operators with T |BX ∗ : (BX ∗ , w∗ ) → (Y, · ) continuous for all n ∈ N. Our results in this case are connected with classical results of Choquet, Odell and Rosenthal.
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2000 Mathematics Subject Classification: Primary 26A33, 30C45; Secondary 33A35
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Mathematics Subject Classification: 47A56, 47A57,47A63
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2000 Mathematics Subject Classification: Primary 47A48, 93B28, 47A65; Secondary 34C94.
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Research partially supported by INTAS grant 97-1644
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Sufficient conditions for the existence of bounded solutions of singularly perturbed impulsive differential equations are obtained. For this purpose integral manifolds are used.
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We consider a finite state automata based method of solving a system of linear Diophantine equations with coefficients from the set {-1,0,1} and solutions in {0,1}.
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2000 Mathematics Subject Classification: 35E45
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Mathematics Subject Classification: 26A33
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Sufficient conditions for the existence of Lp(k)-solutions of linear nonhomogeneous impulsive differential equations with unbounded linear operator are found. An example of the theory of the linear nonhomogeneous partial impulsive differential equations of parabolic type is given.
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A modification of the Nekrassov method for finding a solution of a linear system of algebraic equations is given and a numerical example is shown.