Ask Your Question
1

Reduction mod p of a polynomial

asked 2023-08-18 21:26:34 +0100

tungnt gravatar image

Hi everyone,

I have a question about the factorization of a polynomial modulo a prime ideal that I would like to help with.

Specifically, let $K$ be a number field (for my problem, we can assume that $K=\mathbb{Q}[i]$ or $K=\mathbb{Q}[\omega]$). I have a polynomial $f$ in $O_K[x]$ and a prime ideal $\mathfrak{p}$ in $O_K$ and I want to compute the factorization of $f$ over $O_K/\mathfrak{p}$.

When $K=\mathbb{Q}$, I use the following built-in function.

f=f.change_ring(GF(p))
f.factor()

I wonder whether we can do the same for a general number field.

Thank you for your help.

-Tung

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
2

answered 2023-08-21 00:02:38 +0100

tungnt gravatar image

My collaborator finally figured out how to do this. For your interest, here is how we do it. Let K be the number field, P the prime ideal, and f the polynomial that we want to factor modulo P.

G = K.factor(P)[0][0].residue_field()
f.change_ring(G).factor()

Hope this helps if someone arrives at the same problem in the future.

edit flag offensive delete link more

Comments

You can accept your own answer to mark the question as solved.

slelievre gravatar imageslelievre ( 2023-08-21 22:26:38 +0100 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower

Stats

Asked: 2023-08-18 21:26:34 +0100

Seen: 316 times

Last updated: Aug 21 '23