On the adjunction process over a surface in char.p |
| |
Authors: | M Andreatta E Ballico |
| |
Institution: | 1. Dipartimento di Matematica, Universitá di Milano, Via C. Saldini 50, Milano, Italia 2. Dipartimento di Matematica, Università di Trento, 38050, Povo, TN, Italia
|
| |
Abstract: | Let Ks be the canonical bundle on a non singular projective surface S (over an algebraically closed field F, char F=p) and L be a very ample line bundle on S. Suppose (S,L) is not one of the following pairs: (P2,O(e)), e=1,2, a quadric, a scroll, a Del Pezzo surface, a conic bundle. Then - (Ks?L)2 is spanned at each point by global sections. Let \(\phi :S \to P^N _F \) be the map given by the sections Γ(Ks?L)2, and let φ=s o r its Stein factorization.
- r:S→S′=r(S) is the contraction of a finite number of lines, Ei for i=1,...r, such that Ei·Ei=KS·Ei=?L·Ei=?1.
- If h°(L)≥6 and L·L≥9, then s is an embedding.
|
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|