5
$\begingroup$

Let $(M, J)$ be a Fano projective manifold. Can $(M, -J)$ be general type?

For complex curves and surfaces Kodaira dimension is diffeomorphism invariant so this cannot happen.

$\endgroup$

1 Answer 1

8
$\begingroup$

No. $(M,J)$ and $(M,-J)$ have conjugate pluri-canonical rings, hence have same Kodaira dimension.

Proof. Take a section $\mu$ of $K_{(M, J)}^{\otimes n}$, then $\bar \mu$ is a holomorphic section of $K_{(M,-J)}^{\otimes n}$. And vice versa.

$\endgroup$

You must log in to answer this question.