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Unramified extensions
*October 20, 2009*

*Posted by Akhil Mathew in algebra, algebraic number theory, number theory.*

Tags: discrete valuation rings, Nakayama's lemma, unramified extensions

1 comment so far

Tags: discrete valuation rings, Nakayama's lemma, unramified extensions

1 comment so far

As is likely the case with many math bloggers, I’ve been looking quite a bit at MO and haven’t updated on some of the previous series in a while.

Back to ANT. Today, we tackle the case . We workÂ in the local case where all our DVRs are complete, and all our residue fields are perfect (e.g. finite) (EDIT: I don’t think this works out in the non-local case). I’ll just state these assumptions at the outset. Then, **unramified extensions** can be described fairly explicitly. (more…)