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The Stacks project

Lemma 10.155.12. Let R \to S be a ring map. Let \mathfrak q \subset S be a prime lying over \mathfrak p \subset R. Choose separable algebraic closures \kappa (\mathfrak p) \subset \kappa _1^{sep} and \kappa (\mathfrak q) \subset \kappa _2^{sep}. Let R^{sh} and S^{sh} be the corresponding strict henselizations of R_\mathfrak p and S_\mathfrak q. Given any commutative diagram

\xymatrix{ \kappa _1^{sep} \ar[r]_{\phi } & \kappa _2^{sep} \\ \kappa (\mathfrak p) \ar[r]^{\varphi } \ar[u] & \kappa (\mathfrak q) \ar[u] }

The local ring map R^{sh} \to S^{sh} of Lemma 10.155.10 identifies S^{sh} with the strict henselization of R^{sh} \otimes _ R S at a prime lying over \mathfrak q and the maximal ideal \mathfrak m^{sh} \subset R^{sh}.

Proof. The proof is identical to the proof of Lemma 10.155.8 except that it uses Lemma 10.155.11 instead of Lemma 10.155.7. \square


Comments (2)

Comment #4681 by Peng DU on

In the statement, it uses , which is not introduced.

BTW, this will answer the follow question https://mathoverflow.net/questions/345381/a-question-about-strict-henselian-local-rings in MathOverflow: Let be a finite morphism of schemes, let , here is a separable closure of the residue field . By some results about strict henselian local rings one can see

This result (tag/08HV) will give if .

This further gives a decomposition ( stands for separable degree)

There are also:

  • 8 comment(s) on Section 10.155: Henselization and strict henselization

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