Study on the secondary obstruction classes of singularities

可微流形间一般光滑映射的二次上同调奇点类可以定义为不同于Thom奇点多项式的障碍类。对于4-流形间的一般光滑映射，我们证明了源4-流形的第4阶Stiefel-Whitney类是消除光滑映射尖点奇点的次障碍类。

The secondarycohomology class of singularity for a generic smooth map between differentiable manifolds can be defined as an obstruction class other than the Thom polynomials of singularities. For a generic smooth map between 4-manifolds we have proved that the 4-thStiefel-Whitney class of the source 4-manifold would be the secondary obstructionclass for eliminating cusp singularities of the smooth map.