Lemma 10.37.15. A finite product of normal rings is normal.
Proof. It suffices to show that the product of two normal rings, say $R$ and $S$, is normal. By Lemma 10.21.3 the prime ideals of $R\times S$ are of the form $\mathfrak {p}\times S$ and $R\times \mathfrak {q}$, where $\mathfrak {p}$ and $\mathfrak {q}$ are primes of $R$ and $S$ respectively. Localization yields $(R\times S)_{\mathfrak {p}\times S}=R_{\mathfrak {p}}$ which is a normal domain by assumption. Similarly for $S$. $\square$
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Your email address will not be published.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).
All contributions are licensed under the GNU Free Documentation License.
Comments (0)
There are also: