(Dedekind, Zolotarev) If \(\theta\) is an integral primitive element of \(K/\mathbb{Q}\) and a rational prime \(p\) does not divide \([\mathcal{O}_{K}:\mathbb{Z}[\theta] ]\), then \(p\)’s factorization in \(\mathcal{O}_{K}\) is of the same shape as that of \(\theta\)’s minimal polynomial \(f(x)\) in \(\mathbb{F}_{p}(X)\). That is, there is a natural bijection between primes \(\mathcal{P}|p\) and irreducibles \(\pi | f\) in \(\mathbb{F}_{p}(X)\), and the ramification and residue data match up.
Finally, \(\mathcal{P}= \langle p,\Pi(\theta)\rangle\) for any \(\Pi(X) \in \mathbb{Z}(X)\) such that \(\Pi(X) \equiv_{p} \pi(X)\).
Mostly follows via chinese remainder theorem. See this MSE discussion # Where is this useful?
The condition of monogenicity has to be satisfied. This works for quadratic extensions, cyclotomic fields, and also the maximal real subfield of cyclotomic fields.
This page was updated on October 18, 2023.
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