 Conormal sheaf (source code)

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= Conormal sheaf
{title2=$\mathcal C_{W/V}=\mathcal I_W/\mathcal I_W^2$}

For a closed immersion, this <quasi-coherent sheaf> measures the first-order equations of the subvariety. Its local <module> is $I/I^2$, and its map to the restricted <Kähler differential sheaf> sends the class of $f$ to $df$. This is the definition in https://stacks.math.columbia.edu/tag/01R1[Stacks Project, Section 29.32].

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