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Algebraic number fields, Algebraic integers, Arithmetic Geometry, Elliptic Curves, Function fields, Local fields, Arithmetic groups, Automorphic forms, zeta functions, $L$-functions, Quadratic forms, Quaternion algebras, Homogenous forms, Class groups, Units, Galois theory, Group cohomology, Étale cohomology, Motives, Class field theory, Iwasawa theory, Modular curves, Shimura varieties, Jacobian varieties, Moduli spaces

10 votes

On a minimal algebraic number field which satisfies the principal ideal theorem

The answer to the second question is also "no". Take $k= \mathbb{Q}(\sqrt{-5})$. Then the only non-trivial class capitulates in $H=k(i)$ and it also does in $K=k(\sqrt{-3})$, yet $H$ and $K$ are not i …
Chris Wuthrich's user avatar
5 votes
Accepted

What is the exact meaning of the real period in the $p$-adic formulation of BSD?

Mazur-Tate-Teitelbaum have written their p-adic BSD paper for a modular form of even weight $k\geq 2$ so unless we are dealing with a elliptic curve, we might want to avoid choosing a period. They vie …
Chris Wuthrich's user avatar
10 votes
Accepted

discriminant of subfield of $\mathbb{Q}(\zeta_p)$

The Führerdiskriminantenproduktformel tells you that is it the product of conductors of characters, but all but the trivial character must have conductor $p$.
Chris Wuthrich's user avatar
10 votes
Accepted

class number of prime degree field with prime conductor

Maybe I am making a mistake here, but let me try: Let $H$ be the Hilbert class field of $K$. Then $H\cap \mathbb{Q}(\zeta_p)=K$ as otherwise one prime in there should be totally ramified and unramifi …
Chris Wuthrich's user avatar
2 votes

class group size of cyclotomic field subextension

The $p$-primary part of the class group of $\mathbb{Q}_1$, and in fact all $\mathbb{Q}_n$ in the cyclotomic tower of $\mathbb{Q}$, is trivial for all $p$. This is contained in Proposition 13.22 of Was …
Chris Wuthrich's user avatar
5 votes

Order of $37$-Sylow subgroup of ideal class group of $K_{37} = \Bbb Q(\mu_{37^{n}})$ is know...

Much more than Iwasawa's original theorem is known by now. First of all, the $p$-primary part of the class group stays trivial in the field $K_n=\mathbb{Q}(\mu_{p^{n+1}})$ unless it is already non-tri …
Chris Wuthrich's user avatar
8 votes
Accepted

Capitulation in cyclotomic extensions

Assume $p$ is an irregular prime for which Vandiver's conjecture holds, e.g. $p<12'000'000$. This conjecture asserts that $p$ does not divide the $+$-part of the class group. Then there is no capitu …
Chris Wuthrich's user avatar
7 votes
Accepted

When is this localization map injective, if at all?

Often it is, but not always. For instance if $K=\mathbb{Q}$ then the map is injective if and only if the rank of $E(\mathbb{Q})$ is at most $1$. This is because the $p$-adic elliptic logarithm of a no …
Chris Wuthrich's user avatar
5 votes
Accepted

Splitting of primes in cyclotomic $\mathbb{Z}_p$-extension

For any $\mathbb{Z}_p$-extension the ramification is concentrated among the primes above $p$. Those that are ramified are totally ramified. For the cyclotomic $\mathbb{Z}_p$-extension all places abov …
Chris Wuthrich's user avatar
2 votes

Vanishing of the degree 2 cohomology of a p-adic field with coefficients Q/Z and action of t...

I don't think the action of Frobenius $\phi$ is trivial. The inf-res five term exact sequence reduces to a short exact sequence $$ 0\to \operatorname{Hom}\bigl(G/I, \mathbb{Q}/\mathbb{Z}\bigr)\to \ope …
Chris Wuthrich's user avatar
7 votes
Accepted

Is there something I am missing about the computation of the $p$-part of the class groups of...

[Rather than leaving the comment "Class number formula" for Olivier as a comment, I expand it for other readers of the question, to a partial answer.] Kummer knew in 1850 that the class group of $\mat …
Chris Wuthrich's user avatar
11 votes
Accepted

Oesterlé's unpublished bound on Uniform Boundedness

Yes, this is published as appendix A to chapter 3 in Derickx' PhD thesis available here: https://openaccess.leidenuniv.nl/handle/1887/43186 . The thesis contains, of course, many more interesting resu …
Chris Wuthrich's user avatar
3 votes

applications of Tate-Poitou duality

Three examples of the use of the Poitou-Tate duality: All parity results (Dokchitsers, Mazur-Rubin, Nekovar, ...) for elliptic curve use this duality somewhere. The duality is also crucial for Eule …