Chern numbers and the indices of some elliptic differential operators

Libgober and Wood proved that the Chern number $c_{1}c_{n-1}$ of a $n$-dimensional compact complex manifold can be determined by its Hirzebruch $\chi_{y}$-genus. Inspired by the idea of their proof, we show that, for compact, spin, almost-complex manifolds, more Chern numbers can be determined by the indices of some twisted Dirac and signature operators. As a byproduct, we get a divisibility result of certain characteristic number for such manifolds. Using our method, we give a direct proof of Libgober-Wood's result, which was originally proved by induction.Comment: 9 pages, to appear in Pacific Journal of Mathematic

The cobordism class of the multiple points of immersions

Let f: M -> N be an even codimensional immersion between smooth manifolds. We derive an explicit formula for the Pontrjagin numbers and signature of the multiple point manifolds in terms of singular cohomology of M and N, the maps induced between these by f and the characteristic classes of the normal bundle. The main trick is to solve a recursion in cohomology by the use of (generalized) formal power series.Comment: 17 pages; LaTeX2e document, use of eLaTeX recommended, non-standard packages: xy, pxfonts, pbox. Accepted by Algebraic Geometry and Topology. Corrections and clarifications mainly due to the referee of the journa