Translator's Note |
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v | |
Foreword |
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vii | |
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Chapter 1 Radon Transform of Test Functions and Generalized Functions on a Real Affine Space |
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1 | (74) |
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1 The Radon Transform on a Real Affine Space |
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1 | (20) |
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1.1 Definition of the Radon Transform |
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1 | (3) |
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1.2 Relation between Radon and Fourier Transforms |
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4 | (1) |
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1.3 Elementary Properties of the Radon Transform |
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5 | (3) |
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1.4 The Inverse Radon Transform |
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8 | (4) |
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1.5 Analog of Plancherel's Theorem for the Radon Transform |
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12 | (3) |
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1.6 Analog of the Paley-Wiener Theorem for the Radon Transform |
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15 | (4) |
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1.7 Asymptotic Behavior of Fourier Transforms of Characteristic Functions of Regions |
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19 | (2) |
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2 The Radon Transform of Generalized Functions |
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21 | (34) |
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2.1 Definition of the Radon Transform for Generalized Functions |
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22 | (3) |
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2.2 Radon Transform of Generalized Functions Concentrated on Points and Line Segments |
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25 | (1) |
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2.3 Radon Transform of (x1) λ + δ (x2 ... xn) |
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26 | (1) |
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2.3a Radon Transform of (x1) k + δ (x2 ... xn) for Nonnegative Integer k |
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27 | (4) |
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2.4 Integral of a Function over a Given Region in Terms of Integrals over Hyperplanes |
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31 | (4) |
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2.5 Radon Transform of the Characteristic Function of One Sheet of a Cone |
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35 | (3) |
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38 | (2) |
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2.6 Radon Transform of the Characteristic Function of One Sheet of a Two-Sheeted Hyperboloid |
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40 | (3) |
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2.7 Radon Transform of Homogeneous Functions |
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43 | (1) |
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2.8 Radon Transform of the Characteristic Function of an Octant |
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44 | (7) |
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2.9 The Generalized Hypergeometric Function |
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51 | (4) |
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3 Radon Transforms of Some Particular Generalized Functions |
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55 | (14) |
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3.1 Radon Transforms of the Generalized Functions (P + i0) λ (P -- i0) λ and Pλ. for Nondegenerate Quadratic Forms P |
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56 | (3) |
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59 | (2) |
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3.2 Radon Transforms of (P + c + i0) λ, (P + c - i0) λ, and (P + c) λ + for Nondegenerate Quadratic Forms |
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61 | (2) |
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3.3 Radon Transforms of the Characteristic Functions of Hyperboloids and Cones |
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63 | (3) |
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3.4 Radon Transform of a Delta Function Concentrated on a Quadratic-Surface |
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66 | (3) |
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4 Summary of Radon Transform Formulas |
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69 | (6) |
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Chapter II Integral Transforms in the Complex Domain |
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75 | (58) |
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1 Line Complexes in a Space of Three Complex Dimensions and Related Integral Transforms |
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77 | (17) |
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1.1 Pliicker Coordinates of a Line |
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77 | (1) |
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78 | (2) |
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1.3 A Special Class of Complexes |
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80 | (2) |
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1.4 The Problem of Integral Geometry for a Line Complex |
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82 | (4) |
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1.5 The Inversion Formula. Proof of the Theorem of Section 1.4 |
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86 | (3) |
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1.6 Examples of Complexes |
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89 | (3) |
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1.7 Note on Translation Operators |
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92 | (2) |
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2 Integral Geometry on a Quadratic Surface in a Space of Four Complex Dimensions |
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94 | (21) |
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2.1 Statement of the Problem |
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94 | (1) |
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2.2 Line Generators of Quadratic Surfaces |
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95 | (3) |
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2.3 Integrals of f(z) over Quadratic Surfaces and along Complex Lines |
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98 | (2) |
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2.4 Expression for f(z) on a Quadratic Surface in Terms of Its Integrals along Line Generators |
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100 | (3) |
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2.5 Derivation of the Inversion Formula |
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103 | (4) |
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2.6 Another Derivation of the Inversion Formula |
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107 | (4) |
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2.7 Rapidly Decreasing Functions on Quadratic Surfaces. The Paley-Wiener Theorem |
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111 | (4) |
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3 The Radon Transform in the Complex Domain |
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115 | (18) |
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3.1 Definition of the Radon Transform |
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115 | (2) |
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3.2 Representation off(z) in Terms of Its Radon Transform |
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117 | (4) |
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3.3 Analog of Plancherel's Theorem for the Radon Transform |
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121 | (2) |
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3.4 Analog of the Paley-Wiener Theorem for the Radon Transform |
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123 | (1) |
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3.5 Radon Transform of Generalized Functions |
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124 | (1) |
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125 | (6) |
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3.7 The Generalized Hypergeometric Function in the Complex Domain |
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131 | (2) |
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Chapter III Representations of the Group of Complex Unimodular Matrices in Two Dimensions |
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133 | (69) |
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1 The Group of Complex Unimodular Matrices in Two Dimensions and Some of Its Realizations |
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134 | (5) |
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1.1 Connection with the Proper Lorentz Group |
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134 | (3) |
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1.2 Connection with Lobachevskian and Other Motions |
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137 | (2) |
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2 Representations of the Lorentz Group Acting on Homogeneous Functions of Two Complex Variables |
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139 | (9) |
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2.1 Representations of Groups |
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139 | (2) |
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2.2 The Dx Spaces of Homogeneous Functions |
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141 | (1) |
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2.3 Two Useful Realizations of the Dx |
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142 | (2) |
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2.4 Representation of G on Dx |
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144 | (1) |
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2.5 The Tx(g) Operators in Other Realizations of Dx |
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145 | (2) |
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2.6 The Dual Representations |
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147 | (1) |
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3 Summary of Basic Results concerning Representations on Dx |
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148 | (9) |
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3.1 Irreducibility of Representations on the Dx and the Role of Integer Points |
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148 | (3) |
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3.2 Equivalence of Representations on the Dx and the Role of Integer Points |
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151 | (2) |
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3.3 The Problem of Equivalence at Integer Points |
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153 | (3) |
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3.4 Unitary Representations |
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156 | (1) |
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4 Invariant Bilinear Functionals |
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157 | (21) |
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4.1 Statement of the Problem and the Basic Results |
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152 | (7) |
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4.2 Necessary Condition for Invariance under Parallel Translation and Dilation |
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159 | (4) |
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4.3 Conditions for Invariance under Inversion |
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163 | (2) |
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4.4 Sufficiency of Conditions for the Existence of Invariant Bilinear Functionals (Nonsingular Case) |
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165 | (3) |
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4.5 Conditions for the Existence of Invariant Bilinear Functionals (Singular Case) |
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168 | (6) |
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4.6 Degeneracy of Invariant Bilinear Functionals |
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174 | (1) |
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4.7 Conditionally Invariant Bilinear Functionals |
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175 | (3) |
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5 Equivalence of Representations of G |
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178 | (11) |
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5.1 Intertwining Operators |
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178 | (4) |
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5.2 Equivalence of Two Representations |
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182 | (2) |
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5.3 Partially Equivalent Representations |
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184 | (5) |
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6 Unitary Representations of G |
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189 | (13) |
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6.1 Invariant Hermitian Functionals on Dx |
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189 | (1) |
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6.2 Positive Definite Invariant Hermitian Functionals |
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190 | (3) |
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6.3 Invariant Hermitian Functionals for Noninteger ρ, | ρ | > 1 |
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193 | (3) |
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6.4 Invariant Hermitian Functionals in the Special Case of Integer n1 = n2 |
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196 | (2) |
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6.5 Unitary Representations of G by Operators on Hilbert Space |
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198 | (2) |
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6.6 Subspace Irreducibility of the Unitary Representations |
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200 | (2) |
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Chapter IV Harmonic Analysis on the Group of Complex Unimodular Matrices in Two Dimensions |
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202 | (71) |
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1 Definition of the Fourier Transform on a Group. Statement of the Problems and Summary of the Results |
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202 | (14) |
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1.1 Fourier Transform on the Line |
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202 | (2) |
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204 | (1) |
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1.3 Fourier Transform on G |
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205 | (2) |
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1.4 Domain of Definition of F(x) |
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207 | (2) |
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1.5 Summary of the Results of Chapter IV |
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209 | (4) |
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213 | (3) |
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2 Properties of the Fourier Transform on G |
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216 | (61) |
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216 | (2) |
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2.2 Fourier Transform as Integral Operator |
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218 | (2) |
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2.3 Geometric Interpretation of K (z1, z2; Χ) The Functions φ (z1, z2; λ) and φ (u, v; u' v') |
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220 | (2) |
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2.4 Properties of K (z1, z2 ; Χ) |
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222 | (1) |
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2.5 Continuity of K (z1, z2; χ) |
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223 | (2) |
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2.6 Asymptotic Behavior of K (z1, z2; Χ) |
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225 | (1) |
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2.7 Trace of the Fourier Transform |
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226 | (1) |
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3 Inverse Fourier Transform and Plancherel's Theorem for G |
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227 | (1) |
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3.1 Statement of the Problem |
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227 | (3) |
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3.2 Expression for φ (z1, z2; λ) in Terms of K (z1, z2 ; χ) |
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230 | (2) |
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3.3 Expression for f(g) in Terms of (z1, z2; λ) |
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232 | (3) |
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3.4 Expression for f(g) in Terms of Its Fourier Transform F(Χ) |
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235 | (2) |
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3.5 Analog of Plancherel's Theorem for G |
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237 | (3) |
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3.6 Symmetry Properties of F(x) |
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240 | (2) |
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3.7 Fourier Integral and the Decomposition of the Regular Representation of the Lorentz Group into Irreducible Representations |
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242 | (5) |
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4 Differential Operators on G |
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247 | (9) |
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247 | (1) |
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248 | (2) |
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4.3 Relation between Left and Right Derivative Operators |
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250 | (2) |
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4.4 Commutation Relations for the Lie Operators |
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252 | (1) |
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253 | (1) |
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4.6 Functions on G with Rapidly Decreasing Derivatives |
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254 | (1) |
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4.7 Fourier Transforms of Lie Operators |
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255 | (1) |
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5 The Paley-Wiener Theorem for the Fourier Transform on G |
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256 | (17) |
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5.1 Integrals of f(g) along "Line Generators" |
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257 | (1) |
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5.2 Behavior of φ (u, v; u', v') under Translation and Differentiation of f(g) |
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258 | (2) |
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5.3 Differentiability and Asymptotic Behavior of φ (u, v; u', v') |
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260 | (2) |
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5.4 Conditions on K(z1, z2 ; χ) |
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262 | (3) |
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5.5 Moments of f(g) and Their Expression in Terms of the Kernel |
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265 | (2) |
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5.6 The Paley-Wiener Theorem for the Fourier Transform on G |
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267 | (6) |
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Chapter V Integral Geometry in a Space of Constant Curvature |
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273 | (58) |
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1 Spaces of Constant Curvature |
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274 | (16) |
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1.1 Spherical and Lobachevskian Spaces |
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274 | (2) |
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1.2 Some Models of Lobachevskian Spaces |
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276 | (1) |
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1.3 Imaginary Lobachevskian Spaces |
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277 | (1) |
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1.3a Isotropic Lines of an Imaginary Lobachevskian Space |
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278 | (2) |
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1.4 Spheres and Horospheres in a Lobachevskian Space |
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280 | (2) |
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1.5 Spheres and Horospheres in an Imaginary Lobachevskian Space |
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282 | (3) |
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1.6 Invariant Integration in a Space of Constant Curvature |
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285 | (2) |
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1.7 Integration over a Horosphere |
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287 | (1) |
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1.8 Measures on the Absolute |
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288 | (2) |
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2 Integral Transform Associated with Horospheres in a Lobachevskian Space |
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290 | (14) |
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2.1 Integral Transform Associated with Horospheres |
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291 | (2) |
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2.2 Inversion Formula for n = 3 |
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293 | (7) |
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2.3 Inversion Formula for Arbitrary Dimension |
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300 | (2) |
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2.4 Functions Depending on the Distance from a Point to a Horosphere, and Their Averages |
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302 | (2) |
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3 Integral Transform Associated with Horospheres in an Imaginary Lobachevskian Space |
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304 | (27) |
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3.1 Statement of the Problem and Preliminary Remarks |
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304 | (4) |
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3.2 Regularizing Integrals by Analytic Continuation in the Coordinates |
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308 | (6) |
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3.3 Derivation of the Inversion Formula |
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314 | (5) |
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3.4 Derivation of the Inversion Formula (Continued) |
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319 | (5) |
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3.4a Parallel Isotropic Lines |
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324 | (2) |
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3.5 Calculation of Φ (x, a; μ) |
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326 | (5) |
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Chapter VI Harmonic Analysis on Spaces Homogeneous with Respect to the Lorentz Group |
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331 | (59) |
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1 Homogeneous Spaces and the Associated Representations of the Lorentz Group |
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331 | (18) |
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331 | (1) |
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1.2 Representations of the Lorentz Group Associated with Homogeneous Spaces |
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331 | (1) |
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1.3 The Relation between Representation Theory and Integral Geometry |
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332 | (2) |
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1.4 Homogeneous Spaces and Associated Subgroups of Stability |
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334 | (1) |
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1.5 Examples of Spaces Homogeneous with Respect to the Lorentz Group |
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335 | (4) |
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1.6 Group-Theoretical Definition of Horospheres |
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339 | (6) |
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1.7 Fourier Integral Expansions of Functions on Homogeneous Spaces |
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345 | (4) |
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2 Representations of the Lorentz Group Associated with the Complex Affine Plane and with the Cone, and Their Irreducible Components |
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349 | (7) |
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2.1 Unitary Representations of the Lorentz Group Associated with the Complex Affine Plane |
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349 | (3) |
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2.2 Unitary Representation of the Lorentz Group Associated with the Cone |
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352 | (4) |
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3 Decomposition of the Representation of the Lorentz Group Associated with Lobachevskian Space |
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356 | (8) |
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3.1 Representation of the Lorentz Group Associated with Lobachevskian Space |
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356 | (1) |
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3.2 Decomposition by the Horosphere Method |
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357 | (5) |
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3.3 The Analog of Plancherel's Theorem for Lobachevskian Space |
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362 | (2) |
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4 Decomposition of the Representation of the Lorentz Group Associated with Imaginary Lobachevskian Space |
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364 | (21) |
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4.1 Representation of the Lorentz Group Associated with Imaginary Lobachevskian Space |
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364 | (1) |
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4.2 Decomposition of the Representation Associated with Horospheres of the First Kind |
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365 | (2) |
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4.3 Decomposition of the Representation Associated with Isotropic Lines |
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367 | (6) |
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4.4 Decomposition of the Representation Associated with Imaginary Lobachevskian Space |
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373 | (8) |
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4.5 The Analog of Plancherel's Theorem for Imaginary Lobachevskian Space |
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381 | (2) |
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4.6 Integral Transform Associated with Planes in Lobachevskian Space |
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383 | (2) |
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5 Integral Geometry and Harmonic Analysis on the Point Pairs on the Complex Projective Line |
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385 | (5) |
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Chapter VII Representations of the Group of Real Unimodular Matrices in Two Dimensions |
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390 | (50) |
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1 Representations of the Real Unimodular Matrices in Two Dimensions Acting on Homogeneous Functions of Two Real Variables |
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390 | (5) |
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1.1 The Dx Spaces of Homogeneous Functions |
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390 | (2) |
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1.2 Two Useful Realizations of Dx |
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392 | (1) |
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1.3 Representation of G on Dx |
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392 | (1) |
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1.4 The Tx(g) Operators in Other Realizations of Dx |
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393 | (1) |
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1.5 The Dual Representations |
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394 | (1) |
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2 Summary of the Basic Results concerning Representations on Dx |
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395 | (5) |
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2.1 Irreducibility of Representations on Dx |
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395 | (2) |
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2.2 Equivalence of Representations on Dx and the Role of Integer Points |
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397 | (1) |
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2.3 The Problem of Equivalence at Integer Points |
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398 | (1) |
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2.4 Unitary Representations |
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399 | (1) |
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3 Invariant Bilinear Functionals |
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400 | (13) |
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3.1 Invariance under Translation and Dilation |
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401 | (3) |
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3.2 Necessary and Sufficient Conditions for the Existence of an Invariant Bilinear Functional |
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404 | (5) |
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3.3 Degenerate Invariant Bilinear Functionals for Analytic Representations |
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409 | (2) |
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3.4 Conditionally Invariant Bilinear Functionals |
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411 | (2) |
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4 Equivalence of Two Representations |
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413 | (11) |
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4.1 Intertwining Operators |
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413 | (3) |
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4.2 Equivalence of Two Representations |
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416 | (2) |
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4.3 Partially Equivalent Representations |
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418 | (5) |
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4.4 Other Models of Ft and F+ |
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423 | (1) |
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5 Unitary Representations of G |
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424 | (16) |
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5.1 Existence of an Invariant Hermitian Functional |
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424 | (2) |
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5.2 Positive Definite Invariant Hermitian Functionals (Nonanalytic Representations) |
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426 | (3) |
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5.3 Invariant Hermitian Functionals for Analytic Representations |
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429 | (3) |
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5.4 Invariant Positive Definite Hermitian Functionals on the Analytic Function Spaces F+ and F- |
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432 | (2) |
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5.5 Unitary Representations of G by Operators on Hilbert Space |
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434 | (3) |
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5.6 Inequivalence of the Representations of the Discrete Series |
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437 | (1) |
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5.7 Subspace Irreducibility of the Unitary Representations |
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438 | (2) |
Notes and References to the Literature |
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440 | (2) |
Bibliography |
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442 | (3) |
Index |
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445 | |