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Dec 4 at 17:44 vote accept KAK
Dec 4 at 17:44 vote accept KAK
Dec 4 at 17:44
Dec 4 at 15:55 vote accept KAK
Dec 4 at 15:55
Dec 4 at 15:54 vote accept KAK
Dec 4 at 15:55
Dec 4 at 14:05 comment added Piotr Achinger Freeness ensures that $X\times_{X/G} X \simeq G\times X$, so that descent data for $X\to X/G$ correspond to $G$-equivariant structures. Then flatness of $X\to X/G$ gives you effective descent. If the action is not free, you can take the quotient stack $[X/G]$ and then the equivalence in question is (basically) a tautology.
Dec 4 at 13:29 comment added KAK Thank you for your answer. Does the freeness of the action is optimal situation where we have equality?
Dec 4 at 13:01 comment added Carletto Sorry. I was implicitly supposing that $G* is finite.
S Dec 4 at 13:00 review First answers
Dec 4 at 13:13
S Dec 4 at 13:00 history answered Carletto CC BY-SA 4.0