文摘
Let X be a K3 surface, let C be a smooth curve on X, and let Z be a base point free pencil on C . Then, the Lazarsfeld–Mukai bundle 627" title="Click to view the MathML source">EC,Z of rank 2 associated with C and Z is given by an extension of the torsion free sheaf JZ⊗OX(C) by 6212ee37950f63" title="Click to view the MathML source">OX, where JZ is the ideal sheaf of Z in X. We can see that if C is very ample as a divisor on X , 627" title="Click to view the MathML source">EC,Z is an ACM bundle with respect to 2c1290b51d25de" title="Click to view the MathML source">OX(C). In this paper, by using this fact, we will characterize a necessary condition for 627" title="Click to view the MathML source">EC,Z to be given by an extension of two line bundles on X , by ACM line bundles with respect to 2c1290b51d25de" title="Click to view the MathML source">OX(C).