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8 votes
0 answers
317 views

Finding a cyclic cubic extension of a field

Let $K$ be a field and let $E/K$ be a Galois extension of degree 6 with $\text{Gal}(E/K) = S_3$, the symmetric group on 3 letters. Pick two different transpositions $s_1, s_2$ in $S_3$ (hence $s_1s_2$ ...
thierry stulemeijer's user avatar
7 votes
0 answers
470 views

Explicit $H^2(K, \mu) = Q/Z$?

In the development of local class field theory, a very fundamental theorem is that, for every local field $K$ of characteristic zero, $H^2(K, \mu) \cong \mathbb{Q}/\mathbb{Z}$. $(*)$ Neukirch et al. ...
Evan O'Dorney's user avatar
4 votes
0 answers
143 views

Unramified Galois cohomology

Let $k$ be a local field with absolute Galois group $\Gamma_k$, inertia subgroup $I_k \subset \Gamma_k$, and residue field $\mathbb{F}$. Let $M$ be a finite Galois module over $k$. The unramified ...
Daniel Loughran's user avatar
3 votes
0 answers
141 views

Cohomology of local fields in positive characteristic

It is well-known from local class field theory that the Brauer group $\text{Br}(k)$ of a local field $k$ gets killed as you pass to sufficiently large extensions of $k$. In particular, $\text{Br}(L)(p)...
aspear's user avatar
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3 votes
0 answers
128 views

Galois cohomology with coefficients in the integers of the Lubin-Tate extension

Let $K$ be a $p$-adic local field, and $L$ the Lubin-Tate extension obtained from $K$ by attaching roots of some Lubin-Tate formal $\mathcal{O}_{K}$-module with $Gal(L/K) \simeq \mathcal{O}_{K}^{\...
Piotr Pstrągowski's user avatar
2 votes
0 answers
60 views

Galois Cohomology mod 2 of iterated Laurent series

Let $k$ be an algebraically closed field of characteristic different from two. For $n\geq 1$, set $F_n=k((X_1))\cdots ((X_n))$, and let $F=\displaystyle\bigcup_{n\geq 1}F_n$. If $I=\{i_1,\ldots,i_m\}$...
GreginGre's user avatar
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