Concept
Surface rationnelle
Concepts associés (4)
List of complex and algebraic surfaces
This is a list of named algebraic surfaces, compact complex surfaces, and families thereof, sorted according to their Kodaira dimension following Enriques–Kodaira classification. Projective plane Cone (geometry) Cylinder Ellipsoid Hyperboloid Paraboloid Sphere Spheroid Cayley nodal cubic surface, a certain cubic surface with 4 nodes Cayley's ruled cubic surface Clebsch surface or Klein icosahedral surface Fermat cubic Monkey saddle Parabolic conoid Plücker's conoid Whitney umbrella Châtelet surfaces Dupin
Surface of general type
In algebraic geometry, a surface of general type is an algebraic surface with Kodaira dimension 2. Because of Chow's theorem any compact complex manifold of dimension 2 and with Kodaira dimension 2 will actually be an algebraic surface, and in some sense most surfaces are in this class. Gieseker showed that there is a coarse moduli scheme for surfaces of general type; this means that for any fixed values of the Chern numbers there is a quasi-projective scheme classifying the surfaces of general type with those Chern numbers.
Kodaira dimension
In algebraic geometry, the Kodaira dimension κ(X) measures the size of the canonical model of a projective variety X. Igor Shafarevich in a seminar introduced an important numerical invariant of surfaces with the notation κ. Shigeru Iitaka extended it and defined the Kodaira dimension for higher dimensional varieties (under the name of canonical dimension), and later named it after Kunihiko Kodaira. The canonical bundle of a smooth algebraic variety X of dimension n over a field is the line bundle of n-forms, which is the nth exterior power of the cotangent bundle of X.
Géométrie birationnelle
thumb|right|Le cercle est birationnellement équivalent à la droite. Un exemple d'application birationnelle est la projection stéréographique, représentée ici ; avec les notations du texte, P a pour abscisse 1/t. En mathématiques, la géométrie birationnelle est un domaine de la géométrie algébrique dont l'objectif est de déterminer si deux variétés algébriques sont isomorphes, à un ensemble négligeable près. Cela revient à étudier des applications définies par des fonctions rationnelles plutôt que par des polynômes, ces applications n'étant pas définies aux pôles des fonctions.