PULLBACKS OF kappa CLASSES ON (M)over-bar(0,n)

摘要

The moduli space (M) over bar (0,n) carries a codimension-d Chow class kappa(d). We consider the subspace K-n(d) of A(d)((M) over bar (0,n), Q) spanned by pullbacks of kappa(d) via forgetful maps. We find a permutation basis for K-n(d), and describe its annihilator under the intersection pairing in terms of d-dimensional boundary strata. As an application, we give a new permutation basis of the divisor class group of (M) over bar (0,n).