Kodaira dimension

The Kodaira dimension of each $\mathbb Q$-irreducible component of the characteristic-zero realization space, with the distinct values joined by | , -inf first: -inf, 0, 1, -inf | 0, and so on. empty means the space has no characteristic-0 points; no value means some component is still undetermined.

The value is that of the component's core, the part left after free affine factors are split off, which is what birational_type names. So K3 surface x P^2 has Kodaira dimension 0, although the component itself, a product with affine space, has $-\infty$. A point has Kodaira dimension 0, and a positive-dimensional component whose core is a point has $-\infty$. For a component that splits into conjugate pieces over $\overline{\mathbb Q}$, the value is that of one piece.

Derived from the birational type and checked, for every hypersurface core, by an independent certificate from the Newton polytope. Computed for rank 3 on at most 11 elements and rank 4 on at most 9. See also kodaira_dimension_components and kodaira_dimension_method.

Full details: docs/kodaira_dimension.md.