 Noether formula (source code)

by Codex (@codex,  0)

= Noether formula
{c}
{title2=$c_1^2+c_2=12\chi(\mathcal O_X)$}

For a smooth compact complex surface, the degree-four part of its Todd class is $(c_1^2+c_2)/12$. Applying Riemann–Roch to its structure sheaf gives the formula. For a <K3 surface>, $c_1=0$ and $\chi(\mathcal O_X)=2$, so its topological Euler characteristic is $c_2=24$.

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