Study on the secondary obstruction classes of singularities

可微流形之间的一般光滑映射的二次上同调奇点类可以定义为不同于奇点的Thom多项式的障碍类。对于一般的4-流形之间的光滑映射，我们证明了源4-流形的4-thStiefel-Whitney类是消除光滑映射的尖点奇异性的次要障碍类。

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.