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## representability of a stack

Hallo,

I have the following question. Let $f:X\rightarrow Y$ be a morphism of stacks. Assume I know that $Y$ is representable by an algebraic scheme and that for every scheme $T$ and $\xi\in Y(T)$ the fiber $X\times_{f,\xi}T$ is representable by an algebraic scheme.

Is it true that also $X$ is representable by an algebraic scheme?

Thanks

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Just take $\xi=id\in Y(Y)$. – Olivier Benoist Oct 2 at 17:28