The symmetric action on secondary homotopy groups
arXiv:math/0604030
Abstract
We show that the symmetric track group, which is an extension of the symmetric group associated to the second Stiefel- Withney class, acts as a crossed module on the secondary homotopy group of a pointed space. An application is given to cup-one products in unstable homotopy groups of spheres, generalizing a formula of Barratt-Jones-Mahowald.
We correct a misprint in the presentation of the symmetric track groups