The Stacks project

Lemma 36.18.1. Let $X$ be a scheme. Let $K^\bullet $ be a complex of $\mathcal{O}_ X$-modules whose cohomology sheaves are quasi-coherent. Let $(E, d) = \mathop{\mathrm{Hom}}\nolimits _{\text{Comp}^{dg}(\mathcal{O}_ X)}(K^\bullet , K^\bullet )$ be the endomorphism differential graded algebra. Then the functor

\[ - \otimes _ E^\mathbf {L} K^\bullet : D(E, \text{d}) \longrightarrow D(\mathcal{O}_ X) \]

of Differential Graded Algebra, Lemma 22.35.3 has image contained in $D_\mathit{QCoh}(\mathcal{O}_ X)$.

Proof. Let $P$ be a differential graded $E$-module with property (P) and let $F_\bullet $ be a filtration on $P$ as in Differential Graded Algebra, Section 22.20. Then we have

\[ P \otimes _ E K^\bullet = \text{hocolim}\ F_ iP \otimes _ E K^\bullet \]

Each of the $F_ iP$ has a finite filtration whose graded pieces are direct sums of $E[k]$. The result follows easily. $\square$

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