Flips from 4-folds with isolated complete intersection singularities whose downstairs have rational bi-elephants

Abstract

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-elephant) with only rational singularities, then g carries an inductive structure chained up by blow-ups (La Torre Pendente), and in particular the flip exists. This naturally contains Miles Reid's `Pagoda' as an anti-canonical divisor (=elephant) and its proper transforms.

Free picture (photocopy, 1 sheet) is available, write me your name and postal address at [email protected] (by June 28)

References in corpus (4)

• Deforming Calabi-Yau Threefolds
• Extremal contractions from 4-dimensional manifolds to 3-folds
• Primitive Calabi-Yau Threefolds
• Flips from semi-stable 4-folds whose degenerate fibers are unions of Cartier divisors which are terminal factorial 3-folds