Scrolls and Quartics

In [S 1] Saint-Donat shows how to apply a theorem of Del Pezzo and Bertini (quoted as theorem l below) to recover the main result of [XXX] concerning the projective classification of codimension two cubic varieties. In this paper we show how the samc theorem, and sorne relatcd results, can be used t...

Full description

Bibliographic Details
Author: Xambó Descamps, Sebastián
Format: article
Status:Published version
Publication Date:1982
Country:España
Institution:Universidad de Barcelona
Repository:Dipòsit Digital de la UB
OAI Identifier:oai:diposit.ub.edu:2445/16933
Online Access:https://hdl.handle.net/2445/16933
Access Level:Open access
Keyword:Geometria algebraica
Algebraic geometry
Description
Summary:In [S 1] Saint-Donat shows how to apply a theorem of Del Pezzo and Bertini (quoted as theorem l below) to recover the main result of [XXX] concerning the projective classification of codimension two cubic varieties. In this paper we show how the samc theorem, and sorne relatcd results, can be used to produce an "enumcration" of quartic varieties somcwhat more cxplicit than that given by Swinncrton-Dyer in lS2]. Our main rcsult esscntially says that a codimension 2 quartic variety which is contained in a unique quadric is rationally ruled, so that, by a theorem of Bertini, must be the projection uf a quartic scroll (see theorems 5 ami 6 bclow for complete statements).