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On polarized surfaces of degree three whose adjoint bundles are not spanned. (English) Zbl 0828.14018

Let \((S,L)\) be a pair where \(S\) is a smooth complex surface and \(L\) is a line bundle on \(S\). If \(L\) is very ample it is a classical result of Sommese and Van de Ven that \(K + L\) is generated by global sections as soon as it has any. If \(L\) is only ample and spanned, Reider’s theorem implies that \(K + L\) is spanned unless \((S,L)\) is a scroll under the assumption \(L^2 \geq 5\). This work investigates what happens below Reider. In particular pairs \((S,L)\) with \(L\) ample and spanned, \(L^2 = 3\) and \(K + L\) not spanned are investigated. These surfaces are expressed by \(|L |\) as a triple cover of \(\mathbb{P}^2\). Several general results on these surfaces are obtained. In the case in which \(\text{Kod} (S) \leq 0\) a detailed analysis of the possible numerical invariants of these pairs is conducted.

MSC:

14J10 Families, moduli, classification: algebraic theory
14J60 Vector bundles on surfaces and higher-dimensional varieties, and their moduli
14C20 Divisors, linear systems, invertible sheaves
Full Text: DOI

References:

[1] A.Beauville, Surfaces algebriques complexes. Asterisque54 (1978).
[2] M. Beltrametti, A. Lanteri andM. Palleschi, Algebraic surfaces containing an ample divisor of arithmetic genus two. Ark. Math.25, 189-210 (1987). · Zbl 0645.14015 · doi:10.1007/BF02384443
[3] M. Beltrametti andA. J. Sommese, On generically polarized Gorenstein surfaces of sectional genus two. J. Reine Angew. Math.386, 172-186 (1988). · Zbl 0652.14014
[4] T. Fujita, On hyperelliptic polarized varieties. Tôhoku Math. J.35, 1-44 (1983). · doi:10.2748/tmj/1178229099
[5] T.Fujita, Classification theories of polarized varieties. London Math. Lecture Notes Ser.155 (1990). · Zbl 0743.14004
[6] N. P. Gushel, Very ample divisors on projective bundles over an elliptic curve. Mat. Zametki47, 15-22 (1990).
[7] A. Lanteri andM. Palleschi, About the adjunction process for polarized algebraic surfaces. J. Reine Angew. Math.352, 15-23 (1983). · Zbl 0535.14003
[8] R. Miranda, Triple covers in algebraic geometry. Amer. J. Math.107, 1123-1158 (1985). · Zbl 0611.14011 · doi:10.2307/2374349
[9] C.Okonek, M.Schneider and H.Spindler, Vector bundles on complex projective spaces. Basel-Boston-Stuttgart 1980. · Zbl 0438.32016
[10] R. Pardini, Triple covers in positive characteristic. Ark. Mat.27, 319-341 (1989). · Zbl 0707.14010 · doi:10.1007/BF02386379
[11] I. Reider, Vector bundles of rank 2 and linear systems on algebraic surfaces. Ann. of Math.127, 309-316 (1988). · Zbl 0663.14010 · doi:10.2307/2007055
[12] A. J. Sommese, Hyperplane sections of projective surfaces 1: The adjunction mapping. Duke Math. J.46, 377-401 (1979). · Zbl 0415.14019 · doi:10.1215/S0012-7094-79-04616-7
[13] A. J.Sommese and B.Shiffman, Vanishing theorems on complex manifolds. Basel-Boston-Stuttgart 1985. · Zbl 0578.32055
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