Transformations birationnelles quadratiques de l'espace projectif complexe à trois dimensions
Transformations birationnelles quadratiques de l'espace projectif complexe à trois dimensions
We classify birational quadratic transformations of the three dimensional complex projective space, up to linear isomorphisms of source and target. They are of three kinds, depending on the degree of the inverse, which can be 2,3 or 4. There are 30 different types; in 1871, L. Cremona described 23 of …