Estimates of sections of determinant line bundles on Moduli spaces of pure sheaves on algebraic surfaces

Let X be any smooth simply connected projective surface. We consider some moduli space of pure sheaves of dimension one on X, i.e. ${M_X^H(u)}$ with u?=?(0, L, χ(u)?=?0) and L an effective line bundle on X, together with a series of determinant line bundles associated to ${r\mathcal{O}_X]-n\mathcal{O}_{pt}]}$ in the Grothendieck group of X. Let g _L denote the arithmetic genus of curves in the linear system |L|. For g _L ?≤?2, we give a upper bound of the dimensions of sections of these line bundles by restricting them to a generic projective line in |L|. Our result gives, together with G?ttsche’s computation, a first step of a check for the strange duality for some cases for X a rational surface.