22 citations · 23 across the 4 of their papers we have counts for
4 papers
Characterizations of in arbitrary characteristic
Yasuyuki Kachi, János Kollár
We prove that a smooth projective variety of dimension n is isomorphic to projective n-space iff the canonical class is -(n+1)-times an ample divisor. In characteristic zero this w…
Flips from 4-folds with isolated complete intersection singularities whose downstairs have rational bi-elephants
Yasuyuki Kachi
We shall investigate a flipping contraction g : X -> Y from a 4-fold X with at most isolated complete intersection singularities. If Y has an anti-bi-canonical divisor (=bi-elephan…
Flips from semi-stable 4-folds whose degenerate fibers are unions of Cartier divisors which are terminal factorial 3-folds
Yasuyuki Kachi
We shall investigate flipping contractions from a semi-stable 4-fold whose degenerate fiber is a union of Cartier divisors which are terminal factorial 3-folds. Especially we s…
Extremal contractions from 4-dimensional manifolds to 3-folds
Yasuyuki Kachi
Let be the contraction of an extremal ray of a smooth projective 4-fold such that . Then may have a finite number of 2-dimensional fibers. We shall…