A Characterization of Compactness <strong>in</strong> Banach Spaces with Cont<strong>in</strong>uous L<strong>in</strong>ear <strong>Abstract</strong> Representations of <strong>the</strong> Rotation Group of a Circle. Abdullah Çavu¸s and Mehmet Kunt cavus@ktu.edu.tr, mkunt@ktu.edu.tr Department of Ma<strong>the</strong>matics, Karadeniz Technical University, Trabzon, Turkey Let H be a complex Banach space, T be <strong>the</strong> unit circle {z ∈ C : |z| = 1}, SO(2) be <strong>the</strong> group of all rotations of T, GL(H) be group of all <strong>in</strong>vertible bounded l<strong>in</strong>ear operators on H, α : SO(2) → GL(H) be a cont<strong>in</strong>uous l<strong>in</strong>ear representation, x ∈ H. For all n ∈ Z, n-th Fourier coefficient of x with respect to <strong>the</strong> α is def<strong>in</strong>ed by Pn(x) = 1 � e 2π T −<strong>in</strong>t α(t)(x)dt and <strong>the</strong> Fourier series of x with respect to <strong>the</strong> α is def<strong>in</strong>ed by +∞� n=−∞ Pn(x). (1) The convergence of this series and some properties of Pn(x) are <strong>in</strong>vestigated <strong>in</strong> [5]. In this work, a characterization of compactness <strong>in</strong> Banach space H is given by means of Fourier coefficients Pn(x). One of <strong>the</strong> ma<strong>in</strong> results is as follows: Theorem :Suppose that dimHn < +∞ for all n ∈ Z. Then a closed subset A ⊂ H is compact if and only if for any ε > 0 <strong>the</strong>re exists a natural number N(ε) such that� n n+1 σn(x) − x� < ε for all x ∈ A and n ≥ N(ε). Where, for all n ∈ N ∪ {0}, σn(.) : H → H is a l<strong>in</strong>ear bounded operator which is def<strong>in</strong>ed by σn(x) = 1 n + 1 n� Sk(x) for all x ∈ H, Sk(x) is <strong>the</strong> k-th partial sum of (1) for all k ∈ N ∪ {0} and for all n ∈ Z. References k=0 Hn := {x ∈ H : α(t)(x) = e <strong>in</strong>t x, ∀t ∈ T} [1] Edwards R. E., Fourier Series : A Modern Introduction, Spr<strong>in</strong>ger-Verlag, Berl<strong>in</strong>/Heydelberg/New York, 1982. [2] Kislyakov S. V., Classical <strong>the</strong>mes of Fourier analysis, Commutative harmonic analysis I, General survey, Classical aspects, Encycl. Math. Sci., 15, 113-165 1991. [3] Schechter M., Pr<strong>in</strong>ciples of Functional Analysis, Graduate Studies <strong>in</strong> Ma<strong>the</strong>matics, vol. 36, Prov- idence, R. I. American Ma<strong>the</strong>matical Society, (AMS), 2001. [4] Khadjiev Dj., Çavu¸s A., The imbedd<strong>in</strong>g <strong>the</strong>orem for cont<strong>in</strong>uous l<strong>in</strong>ear representation of <strong>the</strong> rotation group of a circle <strong>in</strong> Banach spaces, Dokl. Acad. Nauk of Uzbekistan, N 7, 8-11, 2000. Page 28
[5] Khadjiev Dj., Çavu¸s A., Fourier series <strong>in</strong> Banach spaces, Inverse and Ill-Posed Problems Series, Ill-Posed and Non-Classical Problems of Ma<strong>the</strong>matical Physics and Analysis, Proceed<strong>in</strong>gs of <strong>the</strong> Inter- national <strong>Conference</strong>, Samarcand, Uzbekistan, Editor-<strong>in</strong>-Chief : M. M. Lavrent’ev, VSP, Utrecht-Boston, 71-80, 2003. [6] Khadjiev Dj., The widest cont<strong>in</strong>uous <strong>in</strong>tegral, J. Math. Anal. Appl. 326, 1101-1115, 2007. Acknowledgement. This work was supported by <strong>the</strong> Commission of Scientific Research Projects of Karadeniz Tech- nical University, Project number: 2010.111.3.1. Page 29
- Page 3 and 4: TABLE OF CONTENTS P a g e | i Shado
- Page 5 and 6: P a g e | iii Sturm Liouville Probl
- Page 7 and 8: P a g e | v Real Time 3D Palmprint
- Page 9 and 10: ��������� ��
- Page 11 and 12: Abstract On the Classifications of
- Page 13 and 14: A Note on the Numerical Solution of
- Page 15 and 16: Abstract A Third-Order of Accuracy
- Page 17 and 18: Boundary Value Problem for a Third
- Page 19 and 20: [18] S. G. Krein, Linear Differenti
- Page 21 and 22: Positivity of Two-dimensional Ellip
- Page 23 and 24: On the Numerical Solution of Ultra
- Page 25 and 26: Abstract Optimal Control Problem fo
- Page 27 and 28: On Stability Of Hyperbolic- Ellipti
- Page 29 and 30: Abstract FUZZY CONTINUOUS DYNAMICAL
- Page 31 and 32: [10] D.L. DeAngelis, R.A. Goldstein
- Page 33 and 34: Bright and dark soliton solutions f
- Page 35: [22] H., Triki, A.M.,Wazwaz, Bright
- Page 39 and 40: Paths of Minimal Length on Suborbit
- Page 41 and 42: On A SUBCLASS OF UNIVALENT FUNCTION
- Page 43 and 44: Approximation by Certain Linear Pos
- Page 45 and 46: PARABOLIC PROBLEMS WITH PARAMETER O
- Page 47 and 48: On the Numerical Solution of a Diff
- Page 49 and 50: [3] Y. Ma, and Y. Ge, Applied Mathe
- Page 51 and 52: A Fuzzy Approach to Multi Objective
- Page 53 and 54: Derivation and numerical study of r
- Page 55 and 56: [11] G.A. Baker, P. Graves-Morris,
- Page 57 and 58: Three Models based Fusion Approach
- Page 59 and 60: The normal inverse Gaussian distrib
- Page 61 and 62: Compact and Fredholm Operators on M
- Page 63 and 64: Abstract Extended Eigenvalues of Di
- Page 65 and 66: A New General Inequality for double
- Page 67 and 68: Exact Solutions of the Schrödinger
- Page 69 and 70: [9] Titeux I., Yakubov Y., Complete
- Page 71 and 72: Positivity of Elliptic Difference O
- Page 73 and 74: Transient and Cycle Structure of El
- Page 75 and 76: Abstract Characterizations of Slant
- Page 77 and 78: Page 69 [20] Struik, D. J., Differe
- Page 79 and 80: Applied Mathematics Analysis of the
- Page 81 and 82: Multibody Railway Vehicle Dynamics
- Page 83 and 84: Existence of Global Solutions for a
- Page 85 and 86: On the stability of the steady-stat
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On the Numerical Solution of Diffus
- Page 89 and 90:
Using expanding method of (G ′ /G
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Weighted Bernstein Inequality for T
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Abstract An Application on Suborbit
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On The First Fundamental Theorem fo
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Abstract Almost Convergence and Gen
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Forecast results in contrast with o
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Page 93 [15] M. El-Shahed, A. Salem
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yields a system of equations which
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Abstract Application of the Trial E
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Oscillation Theorems for Second-Ord
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Abstract On Hadamard Type Integral
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A geometrical approach of an optima
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A Perturbation Solution Procedure f
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Solution of Differential Equations
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Aproximation Properties of a Genera
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Blow up of a solution for a system
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A Note on Some Elementary Geometric
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Abstract Solving Crossmatching Puzz
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Polygonal Approximation of Digital
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Panoramic Image Mosaicing Using Mul
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[9] Naimark, M. A. Linear Differant
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Abstract Chaos in cubic-quintic non
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Semismooth Newton method for gradie
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Multiple solutions for quasilinear
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The Modified Bi-quintic B-spline ba
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The Modified Kudryashov Method for
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Study of an inverse problem that mo
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Abstract Finding Global minima with
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PARAMETER DEPENDENT NOVIER-STOKES L
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7. D. J. Fyfe, The use of cubic spl
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Page 141 An error correction method
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Classification of exact solutions f
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Abstract Numerical Solution of a Hy
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generalized hyperbolic tangent func
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EQUIVALENCE OF AFFINE CURVES Yasemi
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Modified trial equation method for
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Normal Extensions of a Singular Dif