Subelliptic harmonic maps from Carnot groups

For subelliptic harmonic maps from a Carnot group into a Riemannian manifold without boundary, we prove that they are smooth near any -regular point (see Definition 1.3) for sufficiently small . As a consequence, any stationary subelliptic harmonic map is smooth away from a closed set with zero H^Q-2 measure. This extends the regularity theory for harmonic maps (cf. SU], Hf], El], Bf]) to this subelliptic setting.Received: 24 April 2002, Accepted: 30 September 2002, Published online: 17 December 2002Mathematics Subject Classification (2000): 35B65, 58J42