Tagged Questions

30
votes
9answers
4k views

Learning Class Field Theory: Local or Global First?

I've noticed that there seem to be two approaches to learning class field theory. The first is to first learn about local fields and local class field theory, and then prove the ba …
0
votes
0answers
112 views

Evaluation of elements in the residue class field of number/function field

Hi, I have a question. Let $F|\mathbb{F}_q$ be algebraic function field and $P$ is a rational place of $F$. suppose $f \in F$ is regular at $P$. Is there any algorithm to evaluate …
8
votes
3answers
938 views

Elliptic Curves over Global Function Fields

I am currently thinking about a problem, and I feel that by knowing more about elliptic curves over extensions of $\mathbb{F}_q(T)$, for $q$ a power of $p$ say, might lead to insig …
28
votes
1answer
1k views

Is there a “purely algebraic” proof of the finiteness of the class number?

The background is as follows: I have been whittling away at my commutative algebra notes (or, rather at commutative algebra itself, I suppose) recently for the occasion of a course …
19
votes
5answers
1k views

Global fields: What exactly is the analogy between number fields and function fields?

Note: This comes up as a byproduct of Qiaochu's question "What are examples of good toy models in mathematics?" There seems to be a general philosophy that problems over function …
11
votes
4answers
795 views

Dimension of central simple algebra over a global field “built using class field theory”.

If $F$ is a global field then a standard exact sequence relating the Brauer groups of $F$ and its completions is the following: $$0\to Br(F)\to\oplus_v Br(F_v)\to\mathbf{Q}/\mathb …
6
votes
1answer
418 views

Can algebraic number fields be generalized in a similar way to function fields in 1 variable over a finite field?

Global fields consist of finite extensions of $\mathbb{Q}$ (algebraic number fields) and finite extensions of $\mathbb{F}_q(x)$ (function fields in 1 variable over a finite field). …
8
votes
2answers
399 views

Evidence for Q^solv being Pseudo-algebraically-closed

This is a follow-up to the following answer: http://mathoverflow.net/questions/4379/solvable-class-field-theory/4386#4386 in which it is stated as a "folklore" conjecture that th …