The Stacks project

Lemma 87.8.3. In the situation above, if $B$ is pre-admissible, then $A$ is pre-admissible.

Proof. Let $J \subset B$ be a weak ideal of definition. Let $I \subset A$ be an open ideal such that $IB \subset J$. Let $I' \subset A$ be an open ideal. To show that $I$ is an ideal of definition we have to show that $I^ n \subset I'$ for $n \gg 0$. Denote $J' \subset B$ the closure of $I'B$. Then $A/I' \to B/J'$ is faithfully flat, hence injective. Thus in order to show that $I^ n \subset I'$ it suffices to show that $\varphi (I)^ n \subset J'$. This holds for $n \gg 0$ since $\varphi (I) \subset J$, the ideal $J$ is an ideal of definition of $B$, and $J'$ is open in $B$. $\square$


Comments (0)


Post a comment

Your email address will not be published.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.




In order to prevent bots from posting comments, we would like you to prove that you are human. You can do this by filling in the name of the current tag in the following input field. As a reminder, this is tag 0GXN. Beware of the difference between the letter 'O' and the digit '0'.