Cobordism Obstructions to Deforming Isolated Singularities.
Commensurations of the Johnson kernel.
Computer calculation of the degree of maps into the Poincaré homology sphere.
Computing crossed modules induced by an inclusion of a normal subgroup, with applications to homotopy 2-types.
Counting fixed points of a finitely generated subgroup of Aff [C].
Given a finitely generated subgroup G of the group of affine transformations acting on the complex line C, we are interested in the quotient Fix( G)/G. The purpose of this note is to establish when this quotient is finite and in this case its cardinality. We give an application to the qualitative study of polynomial planar vector fields at a neighborhood of a nilpotent singular point.