Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 35416

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

45 votes
Accepted

Has Fermat's Last Theorem per se been used?

Corollary 3.17 in this paper of Stefan Keil uses FLT for exponent 7 to show that if $E/\mathbb{Q}$ is an elliptic curve with a rational 7-torsion point $P$, and $E\rightarrow E'$ is the 7-isogeny with …
Alex B.'s user avatar
  • 13k
19 votes
Accepted

how to compute Hilbert class field of $\Bbb Q(\zeta_{23})$?

The cyclotomic field $K=\mathbb{Q}(\zeta_{23})$ contains the quadratic field $F=\mathbb{Q}(\sqrt{-23})$, and $F$ has class number $3$ (it is the first quadratic field, when those are ordered by absolu …
Alex B.'s user avatar
  • 13k
19 votes
Accepted

How to picture $\mathbb{C}_p$?

You do whatever works for you. Some people think more algebraically, others more geometrically. I certainly don't know what "to picture" means in this context, but then, I am a more algebraic person, …
Alex B.'s user avatar
  • 13k
17 votes
Accepted

Order of Ш (Sha)

No, there are no such examples known. In fact, with the current technology, the two questions are more or less equally hard. That's because for any given prime $p$, you can, in principle, establish fi …
Alex B.'s user avatar
  • 13k
17 votes
0 answers
1k views

Special values of Artin L-functions

This question might be naive and might carry the heuristic that we are living in the best possible world a little too far. If so, I appreciate being told so. Background: Stark's conjecture interprets …
Alex B.'s user avatar
  • 13k
16 votes
Accepted

Regulators of Number fields and Elliptic Curves

Let me first give you a heuristic "reason", why the regulator in the class number formula looks different from the regulator in the Birch and Swinnerton-Dyer conjecture. It is often more convenient (a …
Alex B.'s user avatar
  • 13k
16 votes
Accepted

Is there any conditions on a finite abelian group so that it cannot be class group of any nu...

It follows from the Cohen-Lenstra heuristic that every finite abelian group is expected to be isomorphic to infinitely many class groups of real quadratic fields (even to a positive proportion of real …
Alex B.'s user avatar
  • 13k
14 votes

Heuristics of Cohen-Lenstra-Martinet

The answer to the question as stated is "no". The original Cohen—Lenstra—Martinet heuristics say nothing about the $2$-Sylow subgroup of the class group of a quadratic field. These heuristics were lat …
Alex B.'s user avatar
  • 13k
14 votes
Accepted

Finite order elements of $\mathrm{GL}_d(\mathbb{Z})$ that are conjugate to powers of themselves

The answer is "no" in general. There may be an elementary way of seeing this, but I will frame this in representation theoretic terms and will describe a general construction. The question is equivale …
Alex B.'s user avatar
  • 13k
14 votes
2 answers
1k views

Class groups in dihedral extensions - some sort of Spiegelungssatz?

Let $p$ be an odd prime and let $F/\mathbb{Q}$ be a Galois extension with Galois group $D_{2p}$, let $K$ be the intermediate quadratic extension of $\mathbb{Q}$, and $L$ an intermediate degree $p$ ext …
Alex B.'s user avatar
  • 13k
13 votes

Fermat's last theorem over larger fields

There might well be an elementary construction of infinitely many points (which I cannot think of right now), but in any case, I think that there are experts out there who expect there to be infinitel …
Alex B.'s user avatar
  • 13k
12 votes

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

The answer to your first question is "no". In general, if $K/k$ is a cyclic unramified Galois extension of odd order, then the order of the capitulation kernel (the subgroup of the class group of $k$ …
Alex B.'s user avatar
  • 13k
12 votes

An explicit computation in class field theory

In your particular case, $K^{ab}$ is completely understood, but your field is one of the very few for which such an explicit class field theory is known, so you got lucky. I don't know your backgroun …
Alex B.'s user avatar
  • 13k
10 votes

How to compute Hilbert class field of $\Bbb Q(\zeta_{31})$?

This is a fun question, and I had already been thinking of making some comments on this in the question you link to. Apologies in advance for the long post. Actually, the quadratic subfield of $\mathb …
Alex B.'s user avatar
  • 13k
8 votes
Accepted

What is the ring $A_{\Gamma}$ in the Cohen-Lenstra Heuristics?

The group $\Gamma$ is indeed isomorphic to the Galois groups of the fields in the family, whose class groups one studies. The class groups come with a natural action of $\Gamma$, but under this action …
Alex B.'s user avatar
  • 13k

15 30 50 per page