Zulip Chat Archive

Stream: Is there code for X?

Topic: Algebraic integer conjugate norm bound


Michail Karatarakis (Sep 20 2025 at 23:28):

Do we have this?

Let α\alpha be a non-zero algebraic integer. Then α\alpha has a conjugate α(i)\alpha^{(i)} with α(i)1\lvert \alpha^{(i)} \rvert \geq 1.

Riccardo Brasca (Sep 21 2025 at 09:46):

I don't think we have this precise statement, but it should easy to prove: the absolute value of the norm is a least 1, so it's not possible that all the conjugate have absolute value less than 1.

Riccardo Brasca (Sep 21 2025 at 09:49):

Note that we have NumberField.Embeddings.pow_eq_one_of_norm_eq_one, so we know that, except in the root of unity case, there is a conjugate with absolute value strictly bigger than 1.

Xavier Roblot (Sep 21 2025 at 11:21):

The result should be easy to prove using docs#NumberField.InfinitePlace.one_le_of_lt_one


Last updated: Dec 20 2025 at 21:32 UTC