Lemma 21.17.6. Let $(\mathcal{C}, \mathcal{O})$ be a ringed site. Let $(\mathcal{K}_1^\bullet , \mathcal{K}_2^\bullet , \mathcal{K}_3^\bullet )$ be a distinguished triangle in $K(\textit{Mod}(\mathcal{O}))$. If two out of three of $\mathcal{K}_ i^\bullet $ are K-flat, so is the third.

**Proof.**
Follows from Lemma 21.17.1 and the fact that in a distinguished triangle in $K(\textit{Mod}(\mathcal{O}))$ if two out of three are acyclic, so is the third.
$\square$

## 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Your email address will not be published.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).

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.

## Comments (0)