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1 Historical and Introductory Background |
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3 | (38) |
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3 | (3) |
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1.1.1 History: Topics of the Book |
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3 | (2) |
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1.1.2 Prerequisities: Suggestions for the Reader |
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5 | (1) |
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1.2 Compact Riemann Surfaces and Algebraic Curves |
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6 | (18) |
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1.2.1 Examples and Some Basic Facts |
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6 | (7) |
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13 | (2) |
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1.2.3 An Alternative Approach to Riemann Surfaces of Genus 1 |
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15 | (2) |
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1.2.4 A Moduli Problem for Tori |
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17 | (5) |
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1.2.5 Sketch of a Proof of Theorem 1.1 |
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22 | (2) |
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1.3 Appendix: Existence of Enough Meromorphic Functions |
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24 | (2) |
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1.4 Belyi Functions and Their Dessins |
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26 | (15) |
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26 | (1) |
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1.4.2 Existence of Belyi Functions: Simple Examples |
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27 | (2) |
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29 | (4) |
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33 | (4) |
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37 | (4) |
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41 | (18) |
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2.1 Graphs, Maps, and Hypermaps |
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41 | (13) |
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41 | (4) |
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2.1.2 Algebraic Bipartite Maps |
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45 | (3) |
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2.1.3 Dessins as Hypermaps |
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48 | (3) |
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2.1.4 Morphisms of Hypermaps |
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51 | (1) |
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51 | (2) |
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2.1.6 An Instructive Example |
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53 | (1) |
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2.2 Appendix: The Finite Simple Groups |
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54 | (5) |
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2.2.1 The Cyclic Groups of Prime Order |
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54 | (1) |
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2.2.2 The Alternating Groups |
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55 | (1) |
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2.2.3 The Simple Groups of Lie Type |
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55 | (1) |
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2.2.4 The Sporadic Simple Groups |
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56 | (1) |
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57 | (2) |
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3 Dessins and Triangle Groups |
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59 | (30) |
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3.1 Uniformisation and Fuchsian Groups |
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59 | (19) |
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60 | (4) |
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64 | (4) |
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3.1.3 More General Facts About Fuchsian Groups |
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68 | (3) |
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3.1.4 Triangle Groups and Belyi Functions |
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71 | (1) |
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3.1.5 Inclusions Between Fuchsian Groups |
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72 | (4) |
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3.1.6 Klein's Quartic Curve |
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76 | (2) |
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3.2 Appendix: Group Presentations |
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78 | (2) |
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3.3 From Dessins to Holomorphic Structures |
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80 | (9) |
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80 | (1) |
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3.3.2 Triangle Groups and Bipartite Maps |
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81 | (2) |
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3.3.3 Holomorphic Structures |
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83 | (2) |
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3.3.4 Non-cocompact Triangle Groups |
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85 | (1) |
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86 | (3) |
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89 | (26) |
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89 | (7) |
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4.1.1 Basic Galois Theory |
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89 | (2) |
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4.1.2 The Absolute Galois Group |
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91 | (3) |
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4.1.3 Coverings and Galois Groups |
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94 | (2) |
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4.2 Moduli Fields and Fields of Definition |
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96 | (11) |
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4.2.1 Basic Facts and Definitions |
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96 | (5) |
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4.2.2 Galois Action: An Example and Some Invariants |
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101 | (2) |
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4.2.3 Non-invariants of Galois Action |
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103 | (1) |
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4.2.4 Faithful Galois Action on Families of Dessins |
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104 | (3) |
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4.3 Appendix: Another Proof of Theorem 4.9 |
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107 | (8) |
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110 | (5) |
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5 Quasiplatonic Surfaces, and Automorphisms |
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115 | (38) |
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5.1 Quasiplatonic Surfaces: Construction and Counting |
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115 | (16) |
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5.1.1 Definitions and Properties |
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115 | (2) |
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5.1.2 Hurwitz Groups and Surfaces |
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117 | (4) |
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5.1.3 Kernels and Epimorphisms |
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121 | (2) |
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123 | (2) |
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5.1.5 Counting by Character Theory |
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125 | (3) |
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5.1.6 Counting by Mobius Inversion |
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128 | (3) |
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131 | (8) |
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131 | (3) |
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134 | (2) |
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136 | (3) |
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139 | (3) |
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5.4 Fields of Definition Again |
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142 | (3) |
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5.5 Appendix: Linear and Projective Groups |
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145 | (8) |
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149 | (4) |
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153 | (10) |
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153 | (3) |
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6.2 Classification by Genus |
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156 | (3) |
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6.3 Classification by Group |
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159 | (4) |
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161 | (2) |
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7 Regular Embeddings of Complete Graphs |
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163 | (16) |
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7.1 Examples of Regular Embeddings |
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163 | (4) |
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7.1.1 Examples of Genus 0 and 1 |
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164 | (2) |
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166 | (1) |
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167 | (12) |
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7.2.1 Construction of the Biggs Maps |
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167 | (2) |
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169 | (1) |
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7.2.3 Classifying the Regular Embeddings |
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170 | (5) |
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7.2.4 Regular Embeddings and Cyclotomic Polynomials |
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175 | (2) |
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177 | (2) |
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179 | (14) |
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8.1 A Class of Map Operations |
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179 | (3) |
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8.2 Wilson Operations and Galois Actions |
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182 | (3) |
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8.3 The Group of Operations on Dessins |
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185 | (8) |
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191 | (2) |
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193 | (20) |
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193 | (10) |
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9.1.1 Generalised Paley Maps |
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194 | (3) |
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9.1.2 Complete Bipartite Maps |
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197 | (6) |
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9.2 Regular Dessins and Equations |
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203 | (10) |
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9.2.1 Kp,q-Dessins, Classification |
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203 | (1) |
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9.2.2 Kp,q-Dessins, Abelian Case |
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203 | (2) |
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9.2.3 Kp,q-Dessins, Semidirect Product Case |
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205 | (2) |
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207 | (2) |
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209 | (4) |
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213 | (12) |
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10.1 Abc for Function Fields |
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213 | (5) |
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10.1.1 Digression: Motivation from Number Theory |
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213 | (2) |
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10.1.2 The Polynomial Case |
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215 | (1) |
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10.1.3 Abc on Riemann Surfaces |
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216 | (1) |
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10.1.4 Belyi Functions: The Worst Case |
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217 | (1) |
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10.2 Genus 1 Dessins and Complex Multiplication |
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218 | (7) |
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10.2.1 Unramified Self-covers of Elliptic Curves |
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219 | (1) |
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10.2.2 Complex Multiplication by Roots of Unity |
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220 | (1) |
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10.2.3 Complex Multiplication, General Case |
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221 | (3) |
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224 | (1) |
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225 | (26) |
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11.1 Basic Properties and First Examples |
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225 | (8) |
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225 | (2) |
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11.1.2 Beauville's Original Example |
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227 | (3) |
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11.1.3 Enumeration of Beauville Surfaces |
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230 | (3) |
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11.2 Beauville Structures for Specific Families of Groups |
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233 | (6) |
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11.2.1 Beauville Surfaces and Simple Groups |
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233 | (2) |
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11.2.2 Beauville Structures for Symmetric Groups |
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235 | (2) |
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11.2.3 Beauville Structures for Alternating Groups |
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237 | (1) |
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11.2.4 Beauville Structures for L2(q) |
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238 | (1) |
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11.3 Further Properties of Beauville Surfaces |
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239 | (12) |
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11.3.1 Invariants of a Beauville Surface |
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239 | (4) |
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11.3.2 Real Beauville Surfaces |
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243 | (2) |
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11.3.3 The Action of the Absolute Galois Group on Beauville Surfaces |
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245 | (2) |
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247 | (4) |
Hints for Selected Exercises |
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251 | (6) |
Index |
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257 | |