4
votes
1answer
368 views
Doubt in the proof of Stickelberger’s Theorem
I was going through the proof of Stickelberger's Theorem, as given in the book 'Algebraic Number Theory' by Richard A Mollin, and I am having some problem in understanding the proo …
16
votes
0answers
608 views
+150
Orders in number fields
Let $K$ be a degree $n$ extension of ${\mathbb Q}$ with ring of integers $R$. An order in $K$ is a subring with identity of $R$ which is a ${\mathbb Z}$-module of rank $n$.
Quest …
2
votes
1answer
208 views
Simplifying an algebraic integer expression
I have an expression where the variables are algebraic integers:
$p4 = \frac{p12 - p41 \cdot p21}{p22}$
p12 is degree 48 and p22 is most likely degree 48 too. p41 is degree 32 and …
0
votes
0answers
77 views
Bounding number of solutions to an equation:
I have an equation that I think should not have too many solutions, but I don't see a way to argue this.
Given $a, b, c, N \in \mathbb{N}$, how many positive integer solutions $x, …
1
vote
1answer
92 views
ramification of discrete valuation field
Let $K$ be a discrete valuation field with valuation $v:K\rightarrow \mathbb Z\cup {\infty}$ which is normalized by $v(\pi)=1$ for a prime element $\pi$. Let $v:\overline K\rightar …
8
votes
1answer
353 views
how to visualize the class number of an imaginary quadratic field?
Let me detail the title of the question. I'm trying to give students an intuition of what the class number is.
Let $K=\mathbb{Q}(\sqrt{-d})$, with $d>0$ a square-free integer, be …
7
votes
1answer
327 views
Numbers integrally represented by a ternary cubic form
Given integers $a,b,c,$ and cubic form
$$ f(a,b,c) = a^3 + b^3 + c^3 + a^2 b - a b^2 + 3 a^2 c - a c^2 + b^2 c - b c^2 - 4 a b c $$
$$ f(a,b,c) =
\det \left( \begin{array}{ccc …
2
votes
0answers
60 views
Decompositions of representations of pro-p groups
Let $P$ be a pro-p group. Assume that there is a filtration of $P$ by normal subgroups $P_i$ such that $P_0=P$ and $P_{i+1} < P_i(i\in\mathbb N)$. Let $V$ be an $l$-adic represe …
4
votes
1answer
205 views
Inertia subgroup in the ordinary reduction case when $p=2$
Dear MO,
Let $K/\mathbb{Q}_2$ be a finite extension, and let $E/K$ be an elliptic curve with good ordinary reduction, and such that $\mathbb{Q}_2(j(E))=K$. Let $\rho:\operatorname …
0
votes
0answers
59 views
Artin L- Function properties
Hi, I'm trying to understand the proof of one of the properties of the Artin L-function. I have the following doubts;
Why take on $f_i =|G_{P_i}: H_{P_i}I_{G,P_i}|$, $H_{P_i}I_{G …
1
vote
0answers
62 views
points in $V(\bar K \otimes_{\bar Q} \bar L)$ rational over tensor product of fields
Let V be a variety over a number field, and let K and L be two algebraically closed
What is known about the points of $V(\bar K \otimes_{\bar Q} \bar L )$ ?
Are there results cla …
4
votes
3answers
236 views
Computing certain class numbers modulo 4
Let $p \equiv 5 \pmod{8}, q \equiv 7 \pmod{8}$ be primes and $N = pq$. I want to show that the class number $n$ of $\mathbb{Q}(\sqrt{-N})$ satisfies $n \equiv 2 \pmod{4}$ if $\lef …
2
votes
0answers
99 views
P-adic Weierstrass Lemma for several variables
The p-adic Weiestrass lemma asserts that a power series $f(z)$ with coefficients in the ring of integers of a local field can be factored as $π^n·u(z)·p(z)$ where u(z) is a unit in …
12
votes
1answer
529 views
Principal maximal ideals in Z[x]/(F)
Is there some irreducible $F \in \mathbb{Z}[x]$ such that $\mathbb{Z}[x]/(F)$ has no principal maximal ideal? Equivalently, is it possible that the $1$-dimensional integral domain …
0
votes
1answer
193 views
local field and number field
Let $K$ be a local field (locally compact topological field) of characteristic zero.
Is it true that $K$ is isomorphic to the completion of a number field
under some valuations?
I …

