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Chapter 1 Introduction: What is this book about? |
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1 | (10) |
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1.1 Background: Hopf-Galois theory and Galois module theory |
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1 | (3) |
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1.2 Hopf-Galois structures since 2000 |
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4 | (2) |
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1.3 Galois module theory since 2000 |
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6 | (3) |
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1.4 What's not in this book |
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9 | (1) |
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10 | (1) |
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Part I Hopf-Galois Extensions |
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11 | (152) |
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Chapter 2 Hopf-Galois structures on Galois extensions of fields, regular subgroups, and skew braces |
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13 | (14) |
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13 | (1) |
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2.2 Greither-Pareigis theory |
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14 | (2) |
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2.3 Byott translation theory |
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16 | (2) |
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2.4 Actions by the left regular representations |
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18 | (1) |
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19 | (1) |
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2.6 Working with regular subgroups of Hol(N) |
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19 | (3) |
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22 | (1) |
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23 | (1) |
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2.9 Connecting skew braces with Hopf-Galois structures |
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24 | (1) |
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2.10 Isomorphic skew braces |
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25 | (2) |
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Chapter 3 (Non)-existence results on Hopf-Galois structures |
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27 | (14) |
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27 | (1) |
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3.2 p-groups, p an odd prime, cyclic case |
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28 | (2) |
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30 | (1) |
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3.4 Groups of composite order n that decompose |
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31 | (2) |
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3.5 Cases where G must be isomorphic to N |
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33 | (2) |
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3.6 Realizability when G = Sn or An |
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35 | (1) |
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3.7 Cases where given G, N can be any group with |G| = |N| |
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35 | (1) |
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3.8 If G is abelian or nilpotent, then TV is? |
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36 | (1) |
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3.9 Kohl's non-existence theorem |
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37 | (1) |
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3.10 The case G metabelian and radical algebras |
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38 | (1) |
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3.11 Other realizability results |
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39 | (2) |
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Chapter 4 Hopf-Galois structures arising from fixed point free pairs of homomorphisms |
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41 | (18) |
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41 | (1) |
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4.2 Fixed point free pairs of homomorphisms |
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42 | (1) |
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43 | (3) |
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4.4 The action of L[ N]G on L |
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46 | (2) |
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4.5 Fixed point free endomorphisms |
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48 | (2) |
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50 | (4) |
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4.7 Bi-skew braces and semidirect products |
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54 | (2) |
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4.8 Bi-skew braces and nilpotent rings |
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56 | (3) |
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Chapter 5 Quantitative results |
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59 | (10) |
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59 | (1) |
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5.2 Regular subgroups and nilpotent algebras |
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60 | (1) |
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5.3 Elementary abelian p-groups |
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61 | (1) |
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5.4 Almost trivial algebras |
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62 | (3) |
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5.5 Asymptotic results on e(Cnp,Cnp) for large n |
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65 | (1) |
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5.6 Other counting results |
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66 | (3) |
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Chapter 6 Enumeration of Hopf-Galois structures on Galois extensions of degree mp |
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69 | (14) |
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69 | (1) |
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70 | (1) |
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6.3 Twisted wreath products |
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71 | (2) |
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6.4 Enumeration within Smp |
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73 | (5) |
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6.5 Block systems and Hopf-Galois structures |
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78 | (5) |
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Chapter 7 On the Galois correspondence for Hopf-Galois structures |
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83 | (20) |
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83 | (2) |
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85 | (2) |
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7.3 On the Galois correspondence for Hopf-Galois structures |
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87 | (2) |
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7.4 Kohl's application of Corollary 7.6 |
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89 | (1) |
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90 | (2) |
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7.6 Fixed point free pairs |
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92 | (3) |
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7.7 Radical algebras and the Galois correspondence |
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95 | (2) |
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97 | (1) |
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7.9 Elementary abelian p-groups |
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98 | (1) |
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7.10 Non-normal Hopf-Galois structures |
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99 | (4) |
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Chapter 8 Normality in Hopf-Galois extensions |
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103 | (14) |
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8.1 Normality for Hopf-Galois structures on Galois extensions |
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104 | (4) |
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8.2 Skew braces and normality in Hopf-Galois extensions |
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108 | (3) |
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8.3 Induced Hopf-Galois structures |
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111 | (6) |
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Chapter 9 Descent theory, and the structure of Hopf algebras acting on separable field extensions |
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117 | (28) |
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9.1 General descent theory |
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118 | (8) |
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9.2 Galois descent for Hopf algebras |
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126 | (16) |
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9.3 Absolutely semisimple forms |
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142 | (3) |
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Chapter 10 Hopf-Galois actions on purely inseparable extensions |
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145 | (18) |
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10.1 A little bit of algebraic geometry |
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145 | (7) |
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152 | (7) |
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10.3 Hopf-Galois structures on modular extensions |
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159 | (4) |
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Part II Hopf-Galois Module Theory |
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163 | (134) |
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Chapter 11 Hopf-Galois module theory |
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165 | (24) |
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11.1 The Normal Basis Theorem for Hopf-Galois structures |
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166 | (3) |
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11.2 Hopf orders and Childs' theorem |
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169 | (5) |
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11.3 Associated orders for opposite Hopf-Galois structures |
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174 | (1) |
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11.4 Subextension techniques |
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175 | (4) |
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11.5 Tamely ramified extensions |
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179 | (4) |
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11.6 Extensions of number fields |
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183 | (6) |
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Chapter 12 Hopf orders in group rings |
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189 | (48) |
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12.1 Hopf orders and Galois module theory |
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189 | (2) |
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191 | (4) |
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12.3 Byott's theorem on realizability |
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195 | (2) |
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12.4 Group valuations and Larson orders |
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197 | (7) |
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12.5 Hopf orders in K[ G], G = Cp |
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204 | (6) |
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12.6 Hopf orders in K[ G], G = Cp × Cp, G = Cp2 |
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210 | (3) |
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12.7 Hopf orders in K[ G], G = CpS |
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213 | (2) |
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12.8 General constructions in the cases G -- Cpn, G = Cp |
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215 | (1) |
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12.9 Truncated exponential Hopf orders |
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216 | (2) |
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12.10 Models of μpn for n = 1,2,3 |
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218 | (1) |
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12.11 Hopf orders and realizability |
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219 | (5) |
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12.12 Realizable Hopf orders in K[ Cpn], K[ Cnp] |
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224 | (1) |
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12.13 When K has characteristic p |
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225 | (12) |
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Chapter 13 Ramification theory for separable extensions of local fields |
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237 | (18) |
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237 | (3) |
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13.2 Power series and Herbrand's theorem |
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240 | (7) |
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13.3 Properties of lower ramification breaks |
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247 | (8) |
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Chapter 14 Stable and semistable Hopf-Galois extensions |
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255 | (30) |
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14.1 Bondarko's map ip for Hopf-Galois extensions |
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255 | (6) |
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14.2 Some technical lemmas |
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261 | (5) |
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14.3 Diagrams of elements of L × k L |
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266 | (5) |
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14.4 H-stable and H-semistable extensions |
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271 | (2) |
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14.5 Hopf-Galois module structure |
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273 | (7) |
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14.6 A non-classical example |
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280 | (5) |
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Chapter 15 Hopf-Galois scaffolds |
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285 | (12) |
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285 | (1) |
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15.2 Examples of H-scaffolds |
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286 | (3) |
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15.3 Some basic properties of H-scaffolds |
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289 | (2) |
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15.4 H-semistable extensions and H-scaffolds |
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291 | (2) |
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15.5 Ramified extensions of degree p |
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293 | (4) |
Bibliography |
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297 | (12) |
Index |
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309 | |