Spherical completeness of the non-archimedean ring of Colombeau   generalized numbers
  We show spherical completeness of the ring of Colombeau generalized real (or complex) numbers endowed with the sharp norm. As an application, we establish a Hahn Banach extension theorem for ultra pseudo normed modules (over the ring of generalized numbers) of generalized functions in the sense of Colombeau. 
Eberhard Mayerhofer