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1 | (14) |
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1.1 From Even and Odd Functions to Group Representations |
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1 | (4) |
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1.2 Partial Differential Equations and the Laplace Operator |
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5 | (7) |
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7 | (3) |
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10 | (1) |
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1.2.3 The Mantegna Fresco |
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11 | (1) |
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1.3 What is Spectral Theory? |
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12 | (1) |
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1.4 The Prime Number Theorem |
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13 | (1) |
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14 | (1) |
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2 Norms and Banach Spaces |
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15 | (56) |
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15 | (11) |
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2.1.1 Normed Vector Spaces |
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16 | (5) |
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2.1.2 Semi-Norms and Quotient Norms |
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21 | (2) |
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2.1.3 Isometries are Affine |
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23 | (3) |
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2.1.4 A Comment on Notation |
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26 | (1) |
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26 | (13) |
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2.2.1 Proofs of Completeness |
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29 | (7) |
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2.2.2 The Completion of a Normed Vector Space |
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36 | (2) |
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2.2.3 Non-Compactness of the Unit Ball |
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38 | (1) |
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2.3 The Space of Continuous Functions |
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39 | (16) |
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2.3.1 The Arzela---Ascoli Theorem |
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40 | (2) |
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2.3.2 The Stone---Weierstrass Theorem |
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42 | (6) |
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2.3.3 Equidistribution of a Sequence |
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48 | (3) |
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2.3.4 Continuous Functions in LP Spaces |
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51 | (4) |
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2.4 Bounded Operators and Functionals |
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55 | (7) |
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2.4.1 The Norm of Continuous Functionals on C0(X) |
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60 | (1) |
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61 | (1) |
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2.5 Ordinary Differential Equations |
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62 | (8) |
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2.5.1 The Volterra Equation |
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63 | (3) |
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2.5.2 The Sturm---Liouville Equation |
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66 | (4) |
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70 | (1) |
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3 Hilbert Spaces, Fourier Series, Unitary Representations |
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71 | (50) |
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71 | (15) |
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3.1.1 Definitions and Elementary Properties |
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71 | (4) |
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3.1.2 Convex Sets in Uniformly Convex Spaces |
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75 | (8) |
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3.1.3 An Application to Measure Theory |
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83 | (3) |
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3.2 Orthonormal Bases and Gram---Schmidt |
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86 | (5) |
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3.2.1 The Non-Separable Case |
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90 | (1) |
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3.3 Fourier Series on Compact Abelian Groups |
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91 | (4) |
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95 | (11) |
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3.4.1 Convolution on the Torus |
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97 | (2) |
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3.4.2 Dirichlet and Fejer Kernels |
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99 | (5) |
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3.4.3 Differentiability and Fourier Series |
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104 | (2) |
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3.5 Group Actions and Representations |
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106 | (14) |
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3.5.1 Group Actions and Unitary Representations |
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107 | (3) |
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3.5.2 Unitary Representations of Compact Abelian Groups |
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110 | (1) |
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3.5.3 The Strong (Riemann) Integral |
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111 | (2) |
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3.5.4 The Weak (Lebesgue) Integral |
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113 | (2) |
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3.5.5 Proof of the Weight Decomposition |
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115 | (3) |
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118 | (2) |
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120 | (1) |
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4 Uniform Boundedness and the Open Mapping Theorem |
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121 | (14) |
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121 | (5) |
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4.1.1 Uniform Boundedness and Fourier Series |
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123 | (3) |
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4.2 The Open Mapping and Closed Graph Theorems |
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126 | (7) |
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126 | (2) |
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4.2.2 Proof of the Open Mapping Theorem |
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128 | (2) |
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4.2.3 Consequences: Bounded Inverses and Closed Graphs |
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130 | (3) |
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133 | (2) |
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5 Sobolev Spaces and Dirichlet's Boundary Problem |
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135 | (32) |
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5.1 Sobolev Spaces and Embedding on the Torus |
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135 | (5) |
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5.1.1 L2 Sobolev Spaces on Td |
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135 | (3) |
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5.1.2 The Sobolev Embedding Theorem on Td |
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138 | (2) |
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5.2 Sobolev Spaces on Open Sets |
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140 | (12) |
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144 | (2) |
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5.2.2 Restriction Operators and Traces |
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146 | (3) |
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5.2.3 Sobolev Embedding in the Interior |
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149 | (3) |
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5.3 Dirichlet's Boundary Value Problem and Elliptic Regularity |
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152 | (13) |
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5.3.1 The Semi-Inner Product |
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153 | (2) |
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5.3.2 Elliptic Regularity for the Laplace Operator |
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155 | (5) |
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5.3.3 Dirichlet's Boundary Value Problem |
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160 | (5) |
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165 | (2) |
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6 Compact Self-Adjoint Operators, Laplace Eigenfunctions |
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167 | (42) |
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168 | (6) |
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6.1.1 Integral Operators are Often Compact |
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170 | (4) |
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6.2 Spectral Theory of Self-Adjoint Compact Operators |
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174 | (9) |
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6.2.1 The Adjoint Operator |
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175 | (1) |
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6.2.2 The Spectral Theorem |
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176 | (2) |
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6.2.3 Proof of the Spectral Theorem |
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178 | (3) |
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6.2.4 Variational Characterization of Eigenvalues |
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181 | (2) |
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6.3 Trace-Class Operators |
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183 | (13) |
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6.4 Eigenfunctions for the Laplace Operator |
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196 | (12) |
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6.4.1 Right Inverse and Compactness on the Torus |
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197 | (1) |
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6.4.2 A Self-Adjoint Compact Right Inverse |
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198 | (1) |
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6.4.3 Eigenfunctions on a Drum |
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199 | (2) |
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201 | (7) |
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208 | (1) |
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209 | (44) |
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7.1 The Hahn--Banach Theorem and its Consequences |
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209 | (8) |
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7.1.1 The Hahn--Banach Lemma and Theorem |
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209 | (3) |
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7.1.2 Consequences of the Hahn--Banach Theorem |
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212 | (1) |
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213 | (1) |
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7.1.4 An Application of the Spanning Criterion |
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214 | (3) |
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7.2 Banach Limits, Amenable Groups, Banach-Tarski |
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217 | (10) |
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217 | (1) |
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218 | (5) |
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7.2.3 The Banach-Tarski Paradox |
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223 | (4) |
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227 | (12) |
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228 | (2) |
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7.3.2 The Dual of L4pμ (X) for p > 1 |
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230 | (3) |
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7.3.3 Riesz--Thorin Interpolation |
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233 | (6) |
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7.4 Riesz Representation: The Dual of C(X) |
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239 | (13) |
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240 | (1) |
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7.4.2 Totally Disconnected Compact Spaces |
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240 | (3) |
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243 | (3) |
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7.4.4 Locally Compact σ-Compact Metric Spaces |
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246 | (2) |
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7.4.5 Continuous Linear Functionals on C0(X) |
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248 | (4) |
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252 | (1) |
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8 Locally Convex Vector Spaces |
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253 | (60) |
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8.1 Weak Topologies and the Banach--Alaoglu Theorem |
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253 | (8) |
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8.1.1 Weak* Compactness of the Unit Ball |
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256 | (1) |
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8.1.2 More Properties of the Weak and Weak* Topologies |
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257 | (3) |
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8.1.3 Analytic Functions and the Weak Topology |
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260 | (1) |
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8.2 Applications of Weak* Compactness |
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261 | (29) |
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262 | (8) |
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8.2.2 Elliptic Regularity for the Laplace Operator |
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270 | (8) |
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8.2.3 Elliptic Regularity at the Boundary |
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278 | (12) |
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8.3 Topologies on the space of bounded operators |
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290 | (2) |
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8.4 Locally Convex Vector Spaces |
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292 | (4) |
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8.5 Distributions as Generalized Functions |
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296 | (2) |
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298 | (13) |
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8.6.1 Extreme Points and the Krein--Milman Theorem |
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301 | (3) |
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304 | (7) |
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311 | (2) |
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9 Unitary Operators and Flows, Fourier Transform |
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313 | (40) |
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9.1 Spectral Theory of Unitary Operators |
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313 | (16) |
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9.1.1 Herglotz's Theorem for Positive-Definite Sequences |
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314 | (2) |
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9.1.2 Cyclic Representations and the Spectral Theorem |
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316 | (4) |
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320 | (3) |
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9.1.4 Functional Calculus for Unitary Operators |
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323 | (3) |
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9.1.5 An Application of Spectral Theory to Dynamics |
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326 | (3) |
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9.2 The Fourier Transform |
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329 | (15) |
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9.2.1 The Fourier Transform on L1(Rd) |
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331 | (6) |
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9.2.2 The Fourier Transform on L2(Rd) |
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337 | (3) |
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9.2.3 The Fourier Transform, Smoothness, Schwartz Space |
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340 | (2) |
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9.2.4 The Uncertainty Principle |
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342 | (2) |
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9.3 Spectral Theory of Unitary Flows |
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344 | (8) |
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9.3.1 Positive-Definite Functions; Cyclic Representations |
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344 | (2) |
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346 | (4) |
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350 | (2) |
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352 | (1) |
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10 Locally Compact Groups, Amenability, Property (T) |
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353 | (56) |
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353 | (8) |
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361 | (14) |
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10.2.1 Definitions and Main Theorem |
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362 | (1) |
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10.2.2 Proof of Theorem 10.15 |
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363 | (8) |
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10.2.3 A More Uniform Fømer Set |
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371 | (2) |
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10.2.4 Further Equivalences and Properties |
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373 | (2) |
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375 | (25) |
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10.3.1 Definitions and First Properties |
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375 | (2) |
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377 | (1) |
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10.3.3 Proof of Kazdan's Property (T), Connected Case |
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378 | (6) |
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10.3.4 Proof of Kazdan's Property (T), Discrete Case |
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384 | (8) |
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10.3.5 Iwasawa Decomposition and Geometry of Numbers |
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392 | (8) |
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10.4 Highly Connected Networks: Expanders |
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400 | (8) |
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10.4.1 Constructing an Explicit Expander Family |
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406 | (2) |
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408 | (1) |
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11 Banach Algebras and the Spectrum |
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409 | (24) |
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11.1 The Spectrum and Spectral Radius |
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409 | (8) |
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11.1.1 The Geometric Series and its Consequences |
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411 | (2) |
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11.1.2 Using Cauchy Integration |
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413 | (4) |
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417 | (1) |
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11.3 Commutative Banach Algebras and their Gelfand Duals |
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418 | (7) |
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11.3.1 Commutative Unital Banach Algebras |
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419 | (2) |
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11.3.2 Commutative Banach Algebras without a Unit |
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421 | (1) |
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11.3.3 The Gelfand Transform |
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422 | (1) |
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11.3.4 The Gelfand Transform for Commutative C*-algebras |
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423 | (2) |
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11.4 Locally Compact Abelian Groups |
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425 | (6) |
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11.4.1 The Pontryagin Dual |
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428 | (3) |
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431 | (2) |
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12 Spectral Theory and Functional Calculus |
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433 | (54) |
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12.1 Definitions and Basic Lemmas |
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433 | (4) |
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12.1.1 Decomposing the Spectrum |
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433 | (3) |
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12.1.2 The Numerical Range |
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436 | (1) |
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12.1.3 The Essential Spectrum |
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437 | (1) |
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12.2 The Spectrum of a Tree |
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437 | (6) |
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12.2.1 The Correct Upper Bound for the Summing Operator |
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439 | (2) |
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441 | (1) |
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12.2.3 No Eigenvectors on the Tree |
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442 | (1) |
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12.3 Main Goals: The Spectral Theorem and Functional Calculus |
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443 | (3) |
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12.4 Self-Adjoint Operators |
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446 | (13) |
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12.4.1 Continuous Functional Calculus |
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447 | (4) |
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12.4.2 Corollaries to the Continuous Functional Calculus |
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451 | (2) |
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453 | (1) |
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12.4.4 The Spectral Theorem for Self-Adjoint Operators |
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454 | (4) |
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12.4.5 Consequences for Unitary Representations |
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458 | (1) |
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12.5 Commuting Normal Operators |
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459 | (2) |
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12.6 Spectral Measures and the Measurable Functional Calculus |
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461 | (7) |
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12.6.1 Non-Diagonal Spectral Measures |
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461 | (1) |
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12.6.2 The Measurable Functional Calculus |
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462 | (6) |
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12.7 Projection-Valued Measures |
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468 | (5) |
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12.8 Locally Compact Abelian Groups and Pontryagin Duality |
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473 | (12) |
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12.8.1 The Spectral Theorem for Unitary Representations |
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474 | (3) |
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12.8.2 Characters Separate Points |
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477 | (1) |
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12.8.3 The Plancherel Formula |
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478 | (5) |
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12.8.4 Pontryagin Duality |
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483 | (2) |
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485 | (2) |
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13 Self-Adjoint and Symmetric Operators |
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487 | (16) |
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13.1 Examples and Definitions |
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487 | (4) |
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13.2 Operators of the Form T*T |
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491 | (4) |
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13.3 Self-Adjoint Operators |
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495 | (3) |
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498 | (4) |
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13.4.1 The Friedrichs Extension |
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499 | (1) |
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13.4.2 Cayley Transform and Deficiency Indices |
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500 | (2) |
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502 | (1) |
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14 The Prime Number Theorem |
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503 | (34) |
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503 | (4) |
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14.2 The Selberg Symmetry Formula and Banach Algebra Norm |
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507 | (16) |
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14.2.1 Dirichlet Convolution and Mobius Inversion |
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507 | (2) |
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14.2.2 The Selberg Symmetry Formula |
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509 | (5) |
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14.2.3 Measure-Theoretic Reformulation |
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514 | (3) |
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14.2.4 A Density Function and the Continuity Bound |
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517 | (1) |
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518 | (2) |
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14.2.6 Completing the Proof |
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520 | (3) |
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14.3 Non-Trivial Spectrum of the Banach Algebra |
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523 | (1) |
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14.4 Trivial Spectrum of the Banach Algebra |
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524 | (2) |
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14.5 Primes in Arithmetic Progressions |
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526 | (11) |
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14.5.1 Non-Vanishing of Dirichlet L-function at 1 |
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529 | (8) |
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Appendix A Set Theory and Topology |
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537 | (14) |
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A.1 Set Theory and the Axiom of Choice |
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537 | (1) |
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A.2 Basic Definitions in Topology |
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538 | (3) |
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541 | (4) |
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A.4 Compact Sets and Tychonoff's Theorem |
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545 | (2) |
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547 | (4) |
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Appendix B Measure Theory |
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551 | (12) |
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B.1 Basic Definitions and Measurability |
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551 | (3) |
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B.2 Properties of the Integral |
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554 | (2) |
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556 | (2) |
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B.4 Near-Continuity of Measurable Functions |
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558 | (3) |
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561 | (2) |
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Hints for Selected Problems |
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563 | (26) |
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589 | (4) |
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593 | (7) |
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598 | (2) |
General Index |
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600 | |