Title: Bordism of semi-free $S^1$-actions.
Author: Dev P. Sinha
AMS Class: 57R85 (primary); 55R40 (secondary).
LANL ID: math.AT/0303100 
Addresses: Department of Mathematics, University of Oregon, Eugene OR
Email: dps@math.uoregon.edu 


Abstract:
We calculate the geometric and homotopical (or stable) bordism rings associated 
to semi-free $S^1$ actions on complex manifolds, giving explicit generators for
the geometric theory.  To calculate the geometric theory, we prove a case of 
the geometric realization conjecture, which in general would determine the 
geometric theory in terms of the homotopical.  The determination of 
semi-free actions with isolated fixed points up to cobordism complements 
similar results from symplectic geometry.