Skip to main content

All Questions

2 votes
0 answers
264 views

Unique factorization in 3-sphere coordinate ring

For $n\geqslant 1$ define $$A_n=\mathbb{C}[X_0,X_1,\dots,X_n]\Bigg/\left(\sum_{i=0}^{n}X^2_i-1\right).$$ I would like to prove that $A_3$ is a unique factorization domain. For $A_2$ it is not true ...
Lukas's user avatar
  • 913
0 votes
1 answer
175 views

Prove that the elements $2x$ and $x^2$ have no LCM in the ring of integral polynomials with even coefficient of $x$

Let $A$ be the subring of $\Bbb Z[x]$ consisting of all polynomials with even coefficient of $x$. Prove that the elements $2x$ and $x^2$ have no lowest common multiple. Hints please!
Open Season's user avatar
  • 1,332
1 vote
2 answers
2k views

Prove: There are zero divisors in $\Bbb Z_n$ if and only if $n$ is not prime.

I need to prove there are zero divisors in $\mathbb{Z}_n$ if and only if $n$ is not prime. What should I consider first?
Wes's user avatar
  • 497
4 votes
1 answer
2k views

How can I find decompositions in $\mathbb{Z}[\sqrt{d}]$?

Decompositions in $\mathbb{Z}$ In $\mathbb{Z}$ you can find a decomposition of any element $n \in \mathbb{Z}$ by factorization such that $$n = \prod_{p \in \mathbb{P}} p^{v_p(n)}$$ So for a ...
Martin Thoma's user avatar
  • 9,891
13 votes
2 answers
3k views

$K[x_1, x_2,\dots ]$ is a UFD

I wonder about how to conclude that $R=K[x_1, x_2,\dots ]$ is a UFD for $K$ a field. If $f\in R$ then $f$ is a polynomial in only finitely many variables, how do I prove that any factorization of $f$...
harajm's user avatar
  • 2,157
2 votes
1 answer
176 views

If every irreducible element in $D$ is prime, then $D$ has the unique factorization property.

Suppose every irreducible element in a domain $D$ is prime. I'm trying to prove this implication: In a integral domain $D$, if $a=c_1c_2...c_n$ and $a=d_1d_2...d_m$ ($c_i,d_i$ irreducible), then ...
user74141's user avatar
  • 603
4 votes
2 answers
1k views

Verifying prime factorization equivalence class

I define a relation on $\Bbb N$ as follows: $x \sim y \Longleftrightarrow \ \exists \ j,k \in \Bbb Z$ s.t. $x \mid y^j \ \wedge \ y \mid x^k$ I have shown that $\sim$ is an equivalence relation by ...
Moderat's user avatar
  • 4,467

15 30 50 per page
1
3 4 5 6
7