Maximal degree subsheaves of torsion free sheaves on singular projective curves

被引:2
作者
Ballico, E [1 ]
机构
[1] Univ Trent, Dipartimento Matemat, I-38050 Povo, TN, Italy
关键词
D O I
10.1090/S0002-9947-01-02745-3
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
Fix integers r, k, g with r > k > 0 and g greater than or equal to 2. Let X be an integral projective curve with g := p(a)(X) and E a rank r torsion free sheaf on X which is a flat limit of a family of locally free sheaves on X. Here we prove the existence of a rank k subsheaf A of E such that r(deg(A)) greater than or equal to k(deg(E)) - k(r - k)g. We show that for every g greater than or equal to 9 there is an integral projective curve X, X not Gorenstein, and a rank 2 torsion free sheaf E on X with no rank 1 subsheaf A with 2(deg(A)) greater than or equal to deg(E) - g. We show the existence of torsion free sheaves on non-Gorenstein projective curves with other pathological properties.
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页码:3617 / 3627
页数:11
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