Singular fibers and characteristic classes

Let be a proper generic map between smooth manifolds with dimN−dimM=−1. We explicitly calculate the cohomology class dual to the closure of the set of points in N over which lies a specific singular fiber in terms of characteristic classes of M and N.     

On tertiary exotic characteristic classes

We prove the existence and nontriviality of tertiary exotic characteristic classes extending the results of Peterson and Ravenel for secondary exotic classes.

     

On characteristic classes of Q-manifolds

Characteristic classes are defined for supermanifolds equipped with a homological vector field Q. We construct an infinite series of characteristic classes defined in terms of the second covariant derivatives of Q.     

Secondary characteristic classes of super-foliations

We construct secondary classes for super-foliations of codimension $0+\mathrm{\epsilon }1$ and $1+\mathrm{\epsilon }1$. We indicate how to generalize this construction for any regular super-foliations on super-manifolds. We interpret the secondary classes as classes of foliated flat connections. To cite this article: C. Laurent-Gengoux, C. R. Acad. Sci. Paris, Ser. I 339 (2004).     

On uniqueness of characteristic classes

We give an axiomatic characterization of maps from algebraic K-theory. The results apply to a large class of maps from algebraic K-theory to any suitable cohomology theory or to algebraic K-theory. In particular, we obtain comparison theorems for the Chern character and Chern classes and for the Adams operations and λ-operations on higher algebraic K-theory. We show that the Adams operations and λ-operations defined by Grayson agree with the ones defined by Gillet and Soulé.     

Realizing characteristic classes by manifolds

Let BG be the classifying space for stable spherical fibrations, and let V be a finite dimensional vector subspace of the cohomology algebra H¹(BG; $\text{Z}$₂). We prove that V may be realized by a Poincaré duality space P, which means that if v:P→BG is the Spivak fibration, then v¹ maps V isomorphically onto its image in H¹(P;$\text{Z}$₂). By construction, P is the product of a certain Grassman manifold and a spherical fiber space over a closed smooth manifold.     

A note on characteristic classes

This paper studies the relationship between the sections and the Chern or Pontrjagin classes of a vector bundle by the theory of connection. Our results are natural generalizations of the Gauss-Bonnet Theorem.     

On killing characteristic classes by cobordism

Let M be an n-dimensional, differential, compact and closed manifold and let c be a characteristic class of degree greater or equal to (n+1)/2. We will prove that if the class c anihilates all the characteristic numbers of M, where it enters as a factor, then the manifold M is cobordant to a manifold in which the class c is zero. Also, we will examine the case of manifolds with an extra structure.     

Exotic characteristic classes of quaternionic bundles

For aC ^∞ quaternionic vector bundle, the odd-dimensional real Chern classes vanish, and this allows for a construction of secondary (exotic) characteristic classes associated with a pair of quaternionic structures of a given complex vector bundle. This construction is then applied to obtain exotic characteristic classes associated with an automorphismβ of the holomorphic tangent bundle of a Kähler manifold. These results are the complex analoga of those given for the higher order Maslov classes in [V2].