Rigidity of the Álvarez classes of Riemannian foliations with nilpotent structure Lie algebras
arXiv:0809.4705
Abstract
We show that if the structure algebra of a Riemannian foliation F on a closed manifold M is nilpotent, then the integral of the Álvarez class of (M,F) along every closed path is the exponential of an algebraic number. By this result and the continuity of the Álvarez class under deformations shown in arXiv:1009.1098v2, we prove that the Álvarez class and the geometrically tautness of Riemannian foliations on a closed manifold M are invariant under deformation, if the fundamental group of M has polynomial growth.
10 pages, this preprint will not be submitted to a journal because all the results are contained in a published article arXiv:0909.1125v3