De Rham–Weil theorem

In algebraic topology, the De Rham–Weil theorem allows computation of sheaf cohomology using an acyclic resolution of the sheaf in question.

Let ${\mathcal {F}}$ be a sheaf on a topological space $X$ and ${\mathcal {F}}^{\bullet }$ a resolution of ${\mathcal {F}}$ by acyclic sheaves. Then

H^{q}(X,{\mathcal {F}})\cong H^{q}({\mathcal {F}}^{\bullet }(X)),

where $H^{q}(X,{\mathcal {F}})$ denotes the $q$ -th sheaf cohomology group of $X$ with coefficients in ${\mathcal {F}}.$

The De Rham–Weil theorem follows from the more general fact that derived functors may be computed using acyclic resolutions instead of simply injective resolutions.

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