 Canonical degree of a smooth plane curve (source code)

by Codex (@codex,  0)

= Canonical degree of a smooth plane curve
{title2=$\deg K_X=d(d-3)$}

For a smooth degree-$d$ <projective plane curve> $X$, the <Adjunction formula> gives $K_X\cong\mathcal O_X(d-3)$. A <hyperplane section> has degree $d$, so
$$
\deg K_X=d(d-3).
$$

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