Preface |
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xi | |
Introduction |
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xiii | |
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Chapter 1 Operators on Graphs. Quantum graphs |
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1 | (36) |
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1.1 Main graph notions and notation |
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2 | (3) |
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1.2 Difference operators. Discrete Laplace operators |
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5 | (2) |
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7 | (5) |
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1.4 Differential operators on metric graphs. Quantum graphs |
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12 | (21) |
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1.4.1 Vertex conditions. Finite graphs |
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15 | (7) |
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22 | (1) |
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22 | (2) |
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1.4.4 Examples of vertex conditions |
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24 | (3) |
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27 | (5) |
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1.4.6 Non-local vertex conditions |
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32 | (1) |
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1.5 Further remarks and references |
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33 | (4) |
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Chapter 2 Quantum Graph Operators. Special Topics |
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37 | (28) |
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2.1 Quantum graphs and scattering matrices |
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37 | (7) |
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2.1.1 Scattering on vertices |
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37 | (4) |
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2.1.2 Bond scattering matrix and the secular equation |
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41 | (3) |
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2.2 First order operators and scattering matrices |
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44 | (7) |
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2.3 Factorization of quantum graph Hamiltonians |
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51 | (1) |
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2.4 Index of quantum graph operators |
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52 | (2) |
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2.5 Dependence on vertex conditions |
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54 | (5) |
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2.5.1 Variations in the edge lengths |
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58 | (1) |
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2.6 Magnetic Schrodinger operator |
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59 | (3) |
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2.7 Further remarks and references |
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62 | (3) |
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Chapter 3 Spectra of Quantum Graphs |
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65 | (40) |
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3.1 Basic spectral properties of compact quantum graphs |
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66 | (13) |
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3.1.1 Discreteness of the spectrum |
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66 | (1) |
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3.1.2 Dependence on the vertex conditions |
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67 | (1) |
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3.1.3 Eigenfunction dependence |
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68 | (1) |
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3.1.4 An Hadamard-type formula |
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68 | (3) |
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3.1.5 Generic simplicity of the spectrum |
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71 | (1) |
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3.1.6 Eigenvalue bracketing |
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72 | (4) |
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3.1.7 Dependence on the coupling constant at a vertex |
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76 | (3) |
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79 | (3) |
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3.3 Generalized eigenfunctions |
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82 | (2) |
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3.4 Failure of the unique continuation property. Scars |
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84 | (1) |
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3.5 The ubiquitous Dirichlet-to-Neumann map |
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85 | (5) |
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3.5.1 DtN map for a single edge |
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85 | (2) |
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3.5.2 DtN map for a compact graph with a "boundary" |
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87 | (2) |
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3.5.3 DtN map for a single vertex boundary |
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89 | (1) |
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3.5.4 DtN map and the secular equation |
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89 | (1) |
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3.5.5 DtN map and number of negative eigenvalues |
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90 | (1) |
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3.6 Relations between quantum and discrete graph spectra |
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90 | (2) |
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92 | (9) |
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93 | (2) |
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95 | (1) |
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3.7.3 Derivation of the trace formula |
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96 | (3) |
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3.7.4 Expansion in terms of periodic orbits |
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99 | (1) |
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3.7.5 Other formulations of the trace formula |
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100 | (1) |
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3.8 Further remarks and references |
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101 | (4) |
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Chapter 4 Spectra of Periodic Graphs |
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105 | (24) |
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105 | (2) |
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107 | (8) |
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4.2.1 Floquet transform on combinatorial periodic graphs |
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109 | (3) |
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4.2.2 Floquet transform of periodic difference operators |
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112 | (1) |
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4.2.3 Floquet transform on quantum periodic graphs |
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113 | (1) |
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4.2.4 Floquet transform of periodic operators |
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114 | (1) |
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4.3 Band-gap structure of spectrum |
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115 | (2) |
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115 | (1) |
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116 | (1) |
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4.3.3 Floquet transform in Sobolev classes |
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117 | (1) |
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4.4 Absence of the singular continuous spectrum |
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117 | (1) |
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118 | (3) |
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4.6 Where do the spectral edges occur? |
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121 | (2) |
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4.7 Existence and location of spectral gaps |
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123 | (1) |
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124 | (1) |
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4.9 Further remarks and references |
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124 | (5) |
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Chapter 5 Spectra of Quantum Graphs. Special Topics |
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129 | (28) |
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129 | (5) |
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5.1.1 "Spider" decorations |
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133 | (1) |
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5.2 Zeros of eigenfunctions and nodal domains |
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134 | (14) |
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137 | (1) |
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5.2.2 Bounds on the nodal count |
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138 | (4) |
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5.2.3 Nodal count for special types of graphs |
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142 | (1) |
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5.2.4 Nodal deficiency and Morse indices |
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143 | (5) |
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5.3 Spectral determinants of quantum graphs |
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148 | (2) |
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5.4 Scattering on quantum graphs |
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150 | (3) |
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5.5 Further remarks and references |
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153 | (4) |
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Chapter 6 Quantum Chaos on Graphs |
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157 | (24) |
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6.1 Classical "motion" on graphs |
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158 | (1) |
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6.2 Spectral statistics and random matrix theory |
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159 | (5) |
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6.2.1 Form factor of a unitary matrix |
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161 | (1) |
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162 | (2) |
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6.3 Spectral statistics of graphs |
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164 | (3) |
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6.4 Periodic orbit expansions |
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167 | (12) |
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6.4.1 On time-reversal invariance |
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170 | (1) |
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6.4.2 Diagonal approximation |
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170 | (3) |
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6.4.3 The simplest example of an off-diagonal term |
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173 | (6) |
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6.5 Further remarks and references |
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179 | (2) |
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Chapter 7 Some Applications and Generalizations |
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181 | (28) |
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181 | (5) |
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7.1.1 Can one hear the shape of a quantum graph? |
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183 | (1) |
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7.1.2 Quantum graph isospectrality |
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184 | (1) |
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7.1.3 Can one count the shape of a graph? |
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185 | (1) |
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185 | (1) |
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7.1.5 Discrete "electrical impedance" problem |
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185 | (1) |
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7.2 Other types of equations on metric graphs |
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186 | (2) |
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186 | (1) |
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186 | (1) |
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186 | (1) |
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7.2.4 Reaction-diffusion equations |
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187 | (1) |
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7.2.5 Dirac and Rashba operators |
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187 | (1) |
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7.2.6 Pseudo-differential Hamiltonians |
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187 | (1) |
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7.2.7 Non-linear Schrodinger equation (NLS) |
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188 | (1) |
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188 | (1) |
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7.4 Equations on multistructures |
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188 | (1) |
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7.5 Graph models of thin structures |
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188 | (12) |
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190 | (2) |
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192 | (2) |
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194 | (6) |
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7.6 Quantum graph modeling of various physical phenomena |
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200 | (9) |
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7.6.1 Simulation of quantum graphs by microwave networks |
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200 | (1) |
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7.6.2 Realizability questions |
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200 | (1) |
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7.6.3 Spectra of graphene and carbon nanotubes |
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201 | (4) |
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7.6.4 Vacuum energy and Casimir effect |
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205 | (2) |
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7.6.5 Anderson localization |
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207 | (1) |
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7.6.6 Bose-Einstein condensates |
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207 | (1) |
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7.6.7 Quantum Hall effect |
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207 | (1) |
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7.6.8 Flat band phenomena and slowing down light |
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208 | (1) |
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Appendix A Some Notions of Graph Theory |
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209 | (4) |
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A.1 Graph, edge, vertex, degree |
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209 | (1) |
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210 | (1) |
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210 | (1) |
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A.4 Paths, closed paths, Betti number |
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211 | (1) |
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211 | (1) |
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A.6 Cayley graphs and Schreier graphs |
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212 | (1) |
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Appendix B Linear Operators and Operator-Functions |
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213 | (6) |
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B.2 Some notation concerning linear operators |
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213 | (1) |
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B.2 Fredholm and semi-Fredholm operators. Fredholm index |
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213 | (2) |
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B.3 Analytic Fredholm operator functions |
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215 | (1) |
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B.3.1 Some notions from the several complex variables theory |
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215 | (1) |
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B.3.2 Analytic Fredholm operator functions |
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216 | (3) |
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Appendix C Structure of Spectra |
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219 | (4) |
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C.1 Classification of the points of the spectrum |
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220 | (1) |
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C.2 Spectral theorem and spectrum classification |
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220 | (3) |
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Appendix D Symplectic Geometry and Extension Theory |
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223 | (4) |
Bibliography |
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227 | (40) |
Index |
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267 | |