小平次元
Rational varieties (varieties birational to projective space) have Kodaira dimension formula_5. Abelian varieties (the compact complex tori that are projective) have Kodaira dimension zero. More generally, Calabi–Yau manifolds (in dimension 1, elliptic curves; in dimension 2, abelian surfaces, K3 surfaces, and quotients of those varieties by finite groups) have Kodaira dimension zero (corresponding to admitting Ricci flat metrics).