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Normal canonical surfaces in projective 3-space and plane sextics
Kazuhiro Konno ½ÌÊÚ(ÈÕ±¾Osaka University)
2018-01-01 12:13  »ª¶«Ê¦·¶´óÑ§

Let $S$ be a complex algebraic surface of general type with $p_g=4$. Assume that it is minimal and its canonical map is birational onto its image $\Sigma$. When $\deg \Sigma=5$, $\Sigma$ is a normal surface with at most rational double points. But when $\deg \Sigma$ is greater than $5$, normal $\Sigma$ is very rare. I will bound $K_S^2$ from above, and construct several examples of normal $\Sigma$ when it is of degree $6$.