On the log canonical ring with Kodaira dimension two

We prove that the log canonical ring of a projective log canonical pair with Kodaira dimension two is finitely generated.

Divisorial Models of Normal Varieties

We prove that the canonical ring of a canonical variety in the sense of de Fernex and Hacon is finitely generated. We prove that canonical varieties are Kawamata log terminal (klt) if and only if is finitely generated. We introduce a notion of nefness for non-ℚ-Gorenstein varieties and study some of its properties. We then focus on these properties for non-ℚ-Gorenstein toric varieties.

On the Endomorphism Rings of Local Cohomology Modules

Let R be a commutative Noetherian ring and a a proper ideal of R. We show that if n := gradeRa, then . We also prove that, for a nonnegative integer n such that = 0 for every i ≠ n, if for all i > 0 and z ∈ a, then is a homomorphic image of R, where Rz is the ring of fractions of R with respect to a multiplicatively closed subset ﹛z j | j ⩾ 0﹜ of R. Moreover, if HomR(Rz , R) = 0 for all z ∈ a, then is an isomorphism, where is the canonical ring homomorphism R → .

Derived Category and Canonical Bundle --II

Based on the work of Orlov, Kawamata, and others, this chapter shows that the (numerical) Kodaira dimension and the canonical ring are preserved under derived equivalence. The same techniques can be used to derive the invariance of Hochschild cohomology under derived equivalence. Going one step further, it is shown that the nefness of the canonical bundle is detected by the derived category. The chapter also studies the relation between derived and birational (or rather K-) equivalence. The special case of a central conjecture predicts that two birational Calabi-Yau varieties have equivalent derived categories.