Timeline for what are the epimorphisms in the category of algebraic stacks?
Current License: CC BY-SA 3.0
3 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 20, 2016 at 17:06 | comment | added | Qfwfq | You're probably right. I tend to think of schemes over $\mathbb{C}$ only! | |
| Oct 19, 2016 at 2:44 | comment | added | stupid_question_bot | I'm confused about your answer to 1 (and 2). Are you saying that any nontrivial principal bundle $X\rightarrow Y$ is an epimorphism? In that case can't you just let $X\rightarrow Y$ be any Galois extension of fields ${\rm Spec}\;L\rightarrow{\rm Spec}\;K$, in which case $Spec\;L\rightarrow Spec K$ certainly doesn't satisfy the epimorphism property when $\mathcal{M}$ is say the moduli stack of elliptic curves, and $Spec K\rightrightarrows\mathcal{M}$ is given by two nonisomorphic curves over $K$ which become isomorphic over $L$... | |
| Oct 18, 2016 at 2:20 | history | answered | Qfwfq | CC BY-SA 3.0 |