On the Jager-Kaul theorem concerning harmonic maps

Abstract

In 1983, Jäger and Kaul proved that the equator map u*(x) = (x/|x|, 0) : Bn → Sn is unstable for 3 ≤ n ≤ 6 and a minimizer for the energy functional E(u, Bn) = ∫Bn |∇u|2dx in the class H1,2(Bn, Sn) with u = u* on ∂ Bn when n ≥ 7. In this pa Show more