The Stacks project

Lemma 37.22.5. Let $f : X \to Y$ be a flat morphism of locally Noetherian schemes. If $X$ is Cohen-Macaulay, then $f$ is Cohen-Macaulay and $\mathcal{O}_{Y, f(x)}$ is Cohen-Macaulay for all $x \in X$.

Proof. After translating into algebra this follows from Algebra, Lemma 10.163.3. $\square$


Comments (1)

Comment #10983 by Anonymous on

Apologies if this is already somewhere in the Stacks project, but the cited Lemma 10.163.3 also shows the following.

Let be a Cohen–Macaulay morphism of locally Noetherian schemes. If is such that is Cohen–Macaulay,

then is also Cohen–Macaulay.

And sorry for this, but: I wonder if it's better to use "Cohen–Macaulay" instead of "Cohen-Macaulay", i.e. an n-dash instead of a hyphen.

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The weird formatting above is because the comment box resued to let me typeset the two local rings on the same line...

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  • 4 comment(s) on Section 37.22: Cohen-Macaulay morphisms

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