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1 | (6) |
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7 | (44) |
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9 | (42) |
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2.1 Review of the category of groups |
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10 | (9) |
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2.1.1 Abstract groups: axioms |
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10 | (2) |
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2.1.2 Concrete groups: automorphism groups |
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12 | (4) |
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2.1.3 Normal subgroups and quotients |
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16 | (3) |
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2.2 Groups via generators and relations |
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19 | (12) |
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2.2.1 Generating sets of groups |
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19 | (1) |
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20 | (5) |
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2.2.3 Generators and relations |
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25 | (4) |
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2.2.4 Finitely presented groups |
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29 | (2) |
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2.3 New groups out of old |
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31 | (20) |
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2.3.1 Products and extensions |
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32 | (2) |
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2.3.2 Free products and amalgamated free products |
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34 | (5) |
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39 | (12) |
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Part II Groups → Geometry |
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51 | (114) |
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53 | (22) |
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3.1 Review of graph notation |
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54 | (3) |
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57 | (4) |
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3.3 Cayley graphs of free groups |
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61 | (14) |
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3.3.1 Free groups and reduced words |
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62 | (3) |
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3.3.2 Free groups → trees |
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65 | (1) |
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3.3.3 Trees → free groups |
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66 | (2) |
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68 | (7) |
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75 | (40) |
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4.1 Review of group actions |
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76 | (10) |
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77 | (3) |
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4.1.2 Orbits and stabilisers |
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80 | (3) |
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4.1.3 Application: Counting via group actions |
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83 | (1) |
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84 | (2) |
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4.2 Free groups and actions on trees |
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86 | (9) |
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4.2.1 Spanning trees for group actions |
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87 | (1) |
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4.2.2 Reconstructing a Cayley tree |
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88 | (4) |
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4.2.3 Application: Subgroups of free groups are free |
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92 | (3) |
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95 | (2) |
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4.4 Free subgroups of matrix groups |
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97 | (18) |
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4.4.1 Application: The group SL(2, Z) is virtually free |
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97 | (3) |
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4.4.2 Application: Regular graphs of large girth |
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100 | (2) |
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4.4.3 Application: The Tits alternative |
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102 | (3) |
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105 | (10) |
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115 | (50) |
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5.1 Quasi-isometry types of metric spaces |
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116 | (6) |
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5.2 Quasi-isometry types of groups |
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122 | (5) |
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125 | (2) |
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5.3 Quasi-geodesics and quasi-geodesic spaces |
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127 | (5) |
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5.3.1 (Quasi-)Geodesic spaces |
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127 | (1) |
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5.3.2 Geodesification via geometric realisation of graphs |
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128 | (4) |
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5.4 The Svarc--Milnor lemma |
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132 | (9) |
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5.4.1 Application: (Weak) commensurability |
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137 | (2) |
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5.4.2 Application: Geometric structures on manifolds |
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139 | (2) |
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5.5 The dynamic criterion for quasi-isometry |
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141 | (7) |
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5.5.1 Application: Comparing uniform lattices |
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146 | (2) |
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5.6 Quasi-isometry invariants |
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148 | (17) |
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5.6.1 Quasi-isometry invariants |
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148 | (2) |
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5.6.2 Geometric properties of groups and rigidity |
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150 | (1) |
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5.6.3 Functorial quasi-isometry invariants |
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151 | (5) |
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156 | (9) |
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Part III Geometry of groups |
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165 | (152) |
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167 | (36) |
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6.1 Growth functions of finitely generated groups |
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168 | (2) |
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6.2 Growth types of groups |
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170 | (9) |
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171 | (1) |
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6.2.2 Growth types and quasi-isometry |
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172 | (4) |
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6.2.3 Application: Volume growth of manifolds |
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176 | (3) |
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6.3 Groups of polynomial growth |
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179 | (9) |
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180 | (1) |
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6.3.2 Growth of nilpotent groups |
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181 | (1) |
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6.3.3 Polynomial growth implies virtual nilpotence |
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182 | (2) |
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6.3.4 Application: Virtual nilpotence is geometric |
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184 | (1) |
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6.3.5 More on polynomial growth |
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185 | (1) |
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6.3.6 Quasi-isometry rigidity of free Abelian groups |
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186 | (1) |
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6.3.7 Application: Expanding maps of manifolds |
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187 | (1) |
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6.4 Groups of uniform exponential growth |
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188 | (15) |
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6.4.1 Uniform exponential growth |
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188 | (2) |
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6.4.2 Uniform uniform exponential growth |
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190 | (1) |
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6.4.3 The uniform Tits alternative |
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190 | (2) |
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6.4.4 Application: The Lehmer conjecture |
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192 | (2) |
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194 | (9) |
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203 | (54) |
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7.1 Classical curvature, intuitively |
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204 | (4) |
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7.1.1 Curvature of plane curves |
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204 | (1) |
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7.1.2 Curvature of surfaces in R3 |
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205 | (3) |
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7.2 (Quasi-)Hyperbolic spaces |
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208 | (12) |
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208 | (2) |
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7.2.2 Quasi-hyperbolic spaces |
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210 | (3) |
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7.2.3 Quasi-geodesics in hyperbolic spaces |
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213 | (6) |
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219 | (1) |
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220 | (4) |
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7.4 The word problem in hyperbolic groups |
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224 | (5) |
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7.4.1 Application: "Solving" the word problem |
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225 | (4) |
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7.5 Elements of infinite order in hyperbolic groups |
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229 | (17) |
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229 | (6) |
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235 | (6) |
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241 | (4) |
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7.5.4 Application: Products and negative curvature |
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245 | (1) |
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7.6 Non-positively curved groups |
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246 | (11) |
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250 | (7) |
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257 | (32) |
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258 | (1) |
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259 | (8) |
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8.2.1 Ends of geodesic spaces |
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259 | (3) |
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8.2.2 Ends of quasi-geodesic spaces |
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262 | (2) |
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264 | (3) |
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267 | (10) |
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8.3.1 The Gromov boundary of quasi-geodesic spaces |
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267 | (2) |
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8.3.2 The Gromov boundary of hyperbolic spaces |
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269 | (1) |
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8.3.3 The Gromov boundary of groups |
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270 | (1) |
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8.3.4 Application: Free subgroups of hyperbolic groups |
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271 | (6) |
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8.4 Application: Mostow rigidity |
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277 | (3) |
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280 | (9) |
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289 | (28) |
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9.1 Amenability via means |
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290 | (5) |
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9.1.1 First examples of amenable groups |
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290 | (2) |
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9.1.2 Inheritance properties |
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292 | (3) |
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9.2 Further characterisations of amenability |
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295 | (9) |
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295 | (3) |
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9.2.2 Paradoxical decompositions |
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298 | (2) |
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9.2.3 Application: The Banach-Tarski paradox |
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300 | (2) |
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9.2.4 (Co)Homological characterisations of amenability |
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302 | (2) |
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9.3 Quasi-isometry invariance of amenability |
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304 | (1) |
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9.4 Quasi-isometry vs. bilipschitz equivalence |
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305 | (12) |
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309 | (8) |
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Part IV Reference material |
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317 | (2) |
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319 | (34) |
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A.1 The fundamental group |
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320 | (5) |
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A.1.1 Construction and examples |
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320 | (2) |
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322 | (3) |
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325 | (4) |
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325 | (2) |
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327 | (2) |
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329 | (20) |
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A.3.1 Construction of the hyperbolic plane |
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329 | (1) |
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330 | (2) |
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A.3.3 Symmetry and geodesies |
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332 | (9) |
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A.3.4 Hyperbolic triangles |
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341 | (5) |
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346 | (1) |
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347 | (2) |
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A.4 An invitation to programming |
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349 | (4) |
Bibliography |
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353 | (14) |
Index of notation |
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367 | (6) |
Index |
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373 | |