2
$\begingroup$

The title and tags say it all: I am looking for a clean statement and proof of the equivalence of categories between finite étale covers of a connected $k$-scheme and finite continuous permutation representations of the étale fundamental group $\pi_1(X, \overline{x})$ given by the fiber functor.

I need this result for my thesis, but I do not have the space necessary to prove it, so I would like a clear reference I can cite. This is stated in passing at the start of Section 6 in Szamuely's Galois Group and Fundamental Groups, but the proof consists of various remarks spread out throughout the entirety of the preceding section, and even then there's some work to be done. If possible, I would love a a wholly contained proof so that I can reference this away. I only need the result for reductive group schemes over the algebraic closure of a finite field, so total generality is not necessary.

$\endgroup$
4
  • 3
    $\begingroup$ This is the content of SGA 1, exp. V. In particular Theorem 4.1, and §7 which explains that the theorem applies to connected schemes. $\endgroup$
    – abx
    Apr 30, 2021 at 5:36
  • $\begingroup$ @abx What exactly is SGA 1, exp. V? Apologies, I'm a novice in the field. $\endgroup$ Apr 30, 2021 at 5:48
  • 4
    $\begingroup$ @mskilleter SGA is "Séminaire de Géometrie Algébrique" $\endgroup$ Apr 30, 2021 at 6:02
  • 4
    $\begingroup$ SGA 1 $\endgroup$
    – Will Chen
    Apr 30, 2021 at 8:26

1 Answer 1

4
$\begingroup$

I like the notes from the 2016-2017 edition of the Stanford number theory learning seminar. The result that you want is Theorem 3.4 here.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.