## Abstract Let __Y__ be a nonβnormal del Pezzo surface over β and let __d__ β (__Ο__^β1^~__Y__~)^2^ > 0 be the degree of __Y__. Then we prove that __Ο__^β__d__β4^~__Y__~ is very ample for __d__ = 1, 2.
Exceptional curves on Del Pezzo surfaces
β Scribed by Andreas Leopold Knutsen
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 292 KB
- Volume
- 256
- Category
- Article
- ISSN
- 0025-584X
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β¦ Synopsis
Abstract
We classify all cases of exceptional curves on Del Pezzo surfaces, which turn out to be the smooth plane curves and some other cases with Clifford dimension 3. Moreover, the property of being exceptional holds for all curves in the complete linear system. We use this study to extend the results of Pareschi [17] on the constancy of the gonality and Clifford index of smooth curves in a complete linear system on Del Pezzo surfaces of degrees β₯ 2 to the case of Del Pezzo surfaces of degree 1, where we explicitly classify the cases where the gonality and Clifford index are not constant.
π SIMILAR VOLUMES
A k-very ample line bundle L on a Del Peaao Surface is numerically characterized, improving the results of BIANCOFIOR.E -CERESA in [7]. ample line bundles on surfaces whose Picard group is fully known. k -very ample line bundles on P2, on the Hirzebruch surfaces Fn and on hyperelliptic surfaces are
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## Abstract Let __L__ be a nef line bundle on a Del Pezzo surface. We show that __L__ + __K~S~__ is birationally __k__βvery ample if and only if all the smooth curves in |__L__| have gonality β₯__k__ + 2, and we also find numerical criteria for birational __k__βvery ampleness.