Processing math: 100%

The Stacks project

Lemma 67.28.4. Let S be a scheme. Let f : X \to Y be a morphism of algebraic spaces over S. The following are equivalent:

  1. f is locally of finite presentation,

  2. for every x \in |X| the morphism f is of finite presentation at x,

  3. for every scheme Z and any morphism Z \to Y the morphism Z \times _ Y X \to Z is locally of finite presentation,

  4. for every affine scheme Z and any morphism Z \to Y the morphism Z \times _ Y X \to Z is locally of finite presentation,

  5. there exists a scheme V and a surjective étale morphism V \to Y such that V \times _ Y X \to V is locally of finite presentation,

  6. there exists a scheme U and a surjective étale morphism \varphi : U \to X such that the composition f \circ \varphi is locally of finite presentation,

  7. for every commutative diagram

    \xymatrix{ U \ar[d] \ar[r] & V \ar[d] \\ X \ar[r] & Y }

    where U, V are schemes and the vertical arrows are étale the top horizontal arrow is locally of finite presentation,

  8. there exists a commutative diagram

    \xymatrix{ U \ar[d] \ar[r] & V \ar[d] \\ X \ar[r] & Y }

    where U, V are schemes, the vertical arrows are étale, and U \to X is surjective such that the top horizontal arrow is locally of finite presentation, and

  9. there exist Zariski coverings Y = \bigcup _{i \in I} Y_ i, and f^{-1}(Y_ i) = \bigcup X_{ij} such that each morphism X_{ij} \to Y_ i is locally of finite presentation.

Proof. Omitted. \square


Comments (0)


Your email address will not be published. Required fields are marked.

In your comment you can use Markdown and LaTeX style mathematics (enclose it like $\pi$). A preview option is available if you wish to see how it works out (just click on the eye in the toolbar).

Unfortunately JavaScript is disabled in your browser, so the comment preview function will not work.

All contributions are licensed under the GNU Free Documentation License.