= Skyscraper sheaf
{wiki}
For a point inclusion $i:\{x\}\hookrightarrow X$ and an <abelian group> $A$, the skyscraper sheaf $i_*A$ has sections $A$ on opens containing $x$ and zero on other opens. Its restriction maps are identities or maps to zero. If $A\ne0$, its nonzero <stalks> occur at every point of the closure $\overline{\{x\}}$: exactly those points whose every neighbourhood contains $x$. Thus the familiar assertion that only the stalk at $x$ is nonzero requires $x$ to be a <closed point>. It is always <flasque>, giving the stated <skyscraper sheaf cohomology>.
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