Timeline for Alternative definitions of étale and formally unramified in Wraith
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
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| Jan 3, 2022 at 9:17 | vote | accept | Arrow | ||
| Nov 9, 2021 at 13:23 | answer | added | A.B. | timeline score: 2 | |
| Nov 9, 2021 at 9:26 | comment | added | Leo Alonso | @A.B. Why don't you post this as an answer? | |
| Nov 9, 2021 at 8:25 | comment | added | R. van Dobben de Bruyn | In Tag 00UE, it's actually shown that you can take $n = 1$ in the second definition. | |
| Nov 9, 2021 at 8:08 | comment | added | Arrow | Dear @A.B., thanks for the reference. I fixed the typo. | |
| Nov 9, 2021 at 8:08 | history | edited | Arrow | CC BY-SA 4.0 |
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| Nov 8, 2021 at 21:25 | comment | added | A.B. | These are the "local structure theorems" of unramified and étale algebras. They are equivalent to the definitions with liftings and square-zero ideals. The proofs of the equivalence are not simple as far as I know. An excellent reference for all this is Michel Raynaud, Anneaux locaux henseliens; more precisely, see I. Prop. 8, V. Theorem 1 and Theorem 5. (By the way, the second $B$ in the last isomorphism should be an $A$, I think.) | |
| Nov 8, 2021 at 18:38 | history | asked | Arrow | CC BY-SA 4.0 |