Generalized Whitehead products and homotopy groups of spheres

Abstract

A fundamental problem in algebraic topology, the calculation of homotopy groups π_r(S^n) of spheres, was initiated by studies of several authors; Brouwer's degree, Hopf's invariant and Freudenthal's suspension method. Recently, G. W. Whitehead [22] [23] generalized Hopf's invariant and Freudenthal's invariant to enumerate several non-trivial homotopy groups of spheres....