Example 75.19.5. Let S be a scheme. Let X be a quasi-compact and quasi-separated algebraic space over S. Let (\mathcal{F}_ n) be an inverse system of quasi-coherent sheaves on X. Since DQ_ X is a right adjoint it commutes with products and therefore with derived limits. Hence we see that
where the first R\mathop{\mathrm{lim}}\nolimits is taken in D(\mathcal{O}_ X). In fact, let's write K = R\mathop{\mathrm{lim}}\nolimits \mathcal{F}_ n for this. For any affine U étale over X we have
since cohomology commutes with derived limits and since the quasi-coherent sheaves \mathcal{F}_ n have no higher cohomology on affines. By the computation of R\mathop{\mathrm{lim}}\nolimits in the category of abelian groups, we see that H^ i(U, K) = 0 unless i \in [0, 1]. Then finally we conclude that the R\mathop{\mathrm{lim}}\nolimits in D_\mathit{QCoh}(\mathcal{O}_ X), which is DQ_ X(K) by the above, is in D^ b_\mathit{QCoh}(\mathcal{O}_ X) and has vanishing cohomology sheaves in negative degrees by Lemma 75.19.4.
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