the ramification index and the inertial degree are multiplicative in towers
Theorem.
Let E,F and K be number fields in a tower:
K⊆F⊆E |
and let OE,OF and OK be their rings of integers respectively. Suppose p is a prime ideal
of OK and let P be a prime ideal of OF lying above p, and P is a prime ideal of OE lying above P.
\xymatrixE\ar@-[d]&𝒪E\ar@-[d]&𝒫\ar@-[d]F\ar@-[d]&𝒪F\ar@-[d]&𝔓\ar@-[d]K&𝒪K&𝔭
Then the indices of the extensions, the ramification indices and inertial degrees satisfy:
[E:K] | = | [E:F]⋅[F:K], | (1) | ||
e(𝒫|𝔭) | = | e(𝒫|𝔓)⋅e(𝔓|𝔭), | (2) | ||
f(𝒫|𝔭) | = | f(𝒫|𝔓)⋅f(𝔓|𝔭). | (3) |
Title | the ramification index and the inertial degree are multiplicative in towers |
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Canonical name | TheRamificationIndexAndTheInertialDegreeAreMultiplicativeInTowers |
Date of creation | 2013-03-22 15:06:34 |
Last modified on | 2013-03-22 15:06:34 |
Owner | alozano (2414) |
Last modified by | alozano (2414) |
Numerical id | 5 |
Author | alozano (2414) |
Entry type | Theorem |
Classification | msc 12F99 |
Classification | msc 13B02 |
Classification | msc 11S15 |
Related topic | Ramify |
Related topic | InertialDegree |