The Stacks project

Remark 48.20.12. Let $S$ be a Noetherian scheme and let $\omega _ S^\bullet $ be a dualizing complex. Let $f : X \to Y$ be a finite morphism between schemes of finite type over $S$. Let $\omega _ X^\bullet $ and $\omega _ Y^\bullet $ be dualizing complexes normalized relative to $\omega _ S^\bullet $. Then we have

\[ f_*\omega _ X^\bullet = R\mathop{\mathcal{H}\! \mathit{om}}\nolimits (f_*\mathcal{O}_ X, \omega _ Y^\bullet ) \]

in $D_\mathit{QCoh}^+(f_*\mathcal{O}_ X)$ by Lemmas 48.11.4 and 48.20.8 and the trace map of Example 48.20.11 is the map

\[ \text{Tr}_ f : Rf_*\omega _ X^\bullet = f_*\omega _ X^\bullet = R\mathop{\mathcal{H}\! \mathit{om}}\nolimits (f_*\mathcal{O}_ X, \omega _ Y^\bullet ) \longrightarrow \omega _ Y^\bullet \]

which often goes under the name “evaluation at $1$”.

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Your email address will not be published.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 0AX4. Beware of the difference between the letter 'O' and the digit '0'.