All Questions
Tagged with profinite-groups galois-cohomology
6 questions
2
votes
0
answers
285
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kernel and cokernel of corestriction map in cohomology of a profinite group
Let $G$ be a profinite group, $N$ a normal open subgroup and $A$ a discrete $G$-module. We have a corestriction map $cor: H^1(N, A)_{G/N} \to H^1(G, A)$. Are there any results on the kernel and ...
4
votes
1
answer
238
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No lifts in an exact sequence of profinite groups?
In pg. 24 of his book on Galois cohomology, Serre gives the following exercise:
"Give an example of an extension $1 \to P \to E \to G \to 1$ of profinite groups with the following properties:
(i) $...
3
votes
1
answer
228
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induced isomorphism in continuous cohomology
Suppose that we have a morphism between profinite groups $f: G_{1}\rightarrow G_{2}$ such that $f^{\ast}:H_{cont}^{\ast}(G_{2},A)\rightarrow H_{cont}^{\ast}(G_{1},A) $ is an isomorphism for any finite ...
15
votes
1
answer
2k
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Relations between the cohomology of discrete groups and of profinite groups
Let $G$ be a discrete group and $K$ be the profinite completion of $G$. Let $C_K$ denote the category of contionuous $K$-modules and ${C_K}'$ denotes category of finite continuous $K$-modules. Now for ...
5
votes
1
answer
339
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Open subgroups of the etale fundamental group of $P^1_\mathbb Q\setminus\{0,\infty\}$
Let $G$ be the etale fundamental group of $P^1_\mathbb Q\setminus\{0,\infty\}$. Then $G$ is isomorphic to a semidirect product of $\widehat {\mathbb Z}(1)$ by $ Gal_\mathbb Q$.
Is it true that ...
2
votes
1
answer
507
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a question on continuity of $G$-module for a profinite group $G$
I have seen the following statment somewhere, for example in Appendix B2 on Silverman's book "The Arithmetic of Elliptic Curves" : Let $M$ be an abelian group with discrete topology and $G$ be a ...