Lemma 29.17.3. Let $S$ be a locally Noetherian scheme. The following are equivalent:
$S$ is universally catenary, and
all local rings $\mathcal{O}_{S, s}$ of $S$ are universally catenary.
Lemma 29.17.3. Let $S$ be a locally Noetherian scheme. The following are equivalent:
$S$ is universally catenary, and
all local rings $\mathcal{O}_{S, s}$ of $S$ are universally catenary.
Proof. Assume that all local rings of $S$ are universally catenary. Let $f : X \to S$ be locally of finite type. We know that $X$ is catenary if and only if $\mathcal{O}_{X, x}$ is catenary for all $x \in X$. If $f(x) = s$, then $\mathcal{O}_{X, x}$ is essentially of finite type over $\mathcal{O}_{S, s}$. Hence $\mathcal{O}_{X, x}$ is catenary by the assumption that $\mathcal{O}_{S, s}$ is universally catenary.
Conversely, assume that $S$ is universally catenary. Let $s \in S$. We may replace $S$ by an affine open neighbourhood of $s$ by Lemma 29.17.2. Say $S = \mathop{\mathrm{Spec}}(R)$ and $s$ corresponds to the prime ideal $\mathfrak p$. Any finite type $R_{\mathfrak p}$-algebra $A'$ is of the form $A_{\mathfrak p}$ for some finite type $R$-algebra $A$. By assumption (and Lemma 29.17.2 if you like) the ring $A$ is catenary, and hence $A'$ (a localization of $A$) is catenary. Thus $R_{\mathfrak p}$ is universally catenary. $\square$
Your email address will not be published.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).
All contributions are licensed under the GNU Free Documentation License.
Comments (2)
Comment #231 by Pieter Belmans on
Comment #232 by Johan on