We show that if a flat group scheme acts properly, with finite stabilizers, on an algebraic space, then a quotient exists as a separated algebraic space. More generally we show any flat groupid for… Expand

1. Rational curves and the canonical class 2. Introduction to minimal model program 3. Cone theorems 4. Surface singularities 5. Singularities of the minimal model program 6. Three dimensional flops… Expand

A digital timing system for recording a plurality of timing functions and displaying these functions in digital form. A high-frequency crystal control oscillator provides timing pulses which are fed… Expand

This article contains the classification of Fano 3-folds with B2≥2. There exist exactly 87 types of such 3-folds up to deformations; a Fano 3-fold is isomorphic to a product of Pl and a del Pezzo… Expand

This article contains the classification of Fano 3-folds with B2≥2.There exist exactly 87 types of such 3-folds up to deformations; a Fano 3-fold is isomorphic to a product of Pl and a del Pezzo… Expand